tôi là người Việt Nam ai giúp giải bài này nha bài 2 ạ

Ti L Ngi Vit Nam Ai Gip Gii Bi Ny Nha Bi 2

Answers

Answer 1
-3-x+5=x^2-x-2

-3+5=x^2-2

2=x²-2
-x^2=-4
x^2=4
x=+2 or -2
Answer:
x (1)=-2
x(2)=2

Related Questions

Which statement about proportional relationships is false?
A proportional relationship must graph as a line.
A graph of a proportional relationship must pass through (0, 0).
Each point (or pair) in a proportional relationship must share the same ratio.
O Each point (or pair) in a proportional relationship must share the same difference.
Mark this and return
Save and Exit
Next
Submit

Answers

Answer:

Each point (or pair) in a proportional relationship must share the same difference is the false statement.

Can I add [tex]2\sqrt{3} + 5\sqrt{3}[/tex] further?

Answers

Yes, they can be added and simplified further. 2√3 + 5√3 = 7√3 .

Take √3 as common factor:

2√3 + 5√3

(2 + 5)√3

7√3

The two irrational numbers sums to form another irrational number 7√3 . In decimals that is 12.12435...

[tex] \sf{\qquad\qquad\huge\underline{{\sf Answer}}} [/tex]

Yes, The terms assigned above are alike so they can be added easily by simple algebric method where root number can be treated as a variable.

[tex]\qquad \sf  \dashrightarrow \: 2 \sqrt{3} + 5 \sqrt{3} [/tex]

[tex]\qquad \sf  \dashrightarrow \: (2 + 5) \sqrt{3} [/tex]

[tex]\qquad \sf  \dashrightarrow \: 7 \sqrt{3} [/tex]

Karl’s math class is playing a number game. Each student is given a number card containing the numbers 1 to 6. The rules of the game are that each student must put a cross through two numbers on the card and hand it in to the teacher. The teacher has a bag containing six balls numbered 1 to 6. When all the number cards have been handed in the teacher draws out two balls from the bag. Every student who had chosen the same two numbers shown on the balls wins a prize. If there are 30 students in Karl’s class, how many students are likely to win a prize? Describe your reasoning

Answers

By finding the probability, we can expect that 2 out of the 30 students will win the prize.

How many of the 30 students will win the prize?

First, we should get the probability of winning this game.

Here the students select two numbers out of 6, just to make the calculations let's say that these numbers are 1 and 2.

Now, we need to get these two numbers in two balls. The probability of getting the ball with the number 1 out of the 6 balls is:

p = 1/6

The probability of getting the ball with the number 2 out of the remaining 5 balls (because we already got one) is:

q = 1/5

The joint probability is then:

P = 2*(1/6)*(1/5) = 1/15.

Where the factor 2 comes to take in account the permutations, for the case where we first draw the number 2 and then the number 1.

Then the expected number of students that will win is equal to the probability times the total number of students:

(1/15)*30 = 2

So out of the 30 students, we can expect that 2 will win.

If you want to learn more about probability:

https://brainly.com/question/25870256

#SPJ1

Error Analysis Your classmate says that there is not enough information to determine whether the two triangles below are congruent. Is your classmate correct? Explain.

Answers

Answer:

Your classmate says that there is not enough information to determine whether the two triangles below are congruent. Is your classmate correct?

yes it is

The two triangles are congruent triangles by RHS theorem of congruent triangles

What are Congruent Triangles?

Transformations change the size or position of shapes. Congruent shapes are identical, but may be reflected, rotated or translated. Scale factors can increase or decrease the size of a shape. Congruent Triangles simply mean the triangles that possess the same size and shape

The three sides are equal (SSS: side, side, side)

Two angles are the same and a corresponding side is the same (ASA: angle, side, angle)

Two sides are equal and the angle between the two sides is equal (SAS: side, angle, side)

A right angle, the hypotenuse and a corresponding side are equal (RHS, right angle, hypotenuse, side)

Given data ,

Let the first triangle be represented as ΔMLJ

Let the second triangle be represented as ΔLJK

Now , the measure of ∠MLJ = 90°

The measure of ∠LJK = 90°

The measure of side MJ = measure of side LK

So , the two sides of the triangles are similar and they have a common hypotenuse

Therefore , the triangles are congruent by right angle, the hypotenuse and a corresponding side are equal (RHS, right angle, hypotenuse, side)

Hence , the triangles are congruent

To learn more about congruent triangles click :

https://brainly.com/question/26131452

#SPJ2

Please help! To solve the equation 1.75n = 7 for n, what operation must be applied to both sides in order to isolate the variable n?

Answers

Answer:

C

Step-by-step explanation:

1.75n = 7 ( to isolate n divide both sides by 1.75 )

n = [tex]\frac{7}{1.75}[/tex] = 4

Answer:

c.)  Divide by 1.75

Step-by-step explanation:

Given equation:

⇒ 1.75n = 7

Here the coefficient of n which is 1.75 needs to be removed. There is only one way of doing that - by dividing both sides by 1.75.

When done so:

⇒ 1.75n/1.75 = 7/1.75

⇒ n = 4

Solve the quadratic function by factoring.
y = 4x² 13x + 10

Answers

Answer: [tex]x=-\frac{5}{4}[/tex] and [tex]x=-2[/tex]

Step-by-step explanation:

To factor an equation in the form of [tex]ax^2+bx+c[/tex] you need to find the value of [tex]ac[/tex]. So first solve for that

[tex](4)(10) = 40[/tex]

Now we need to find two numbers that add up to b and multiply together to make ac. In this case those numbers are 5 and 8 since 5+8=13 and (5)(8)=40

Now split 13x into 5x+8x and solve by grouping

[tex]4x^2+5x+8x+10\\(4x^2+5x)+(8x+10)[/tex]

Factor out the GCF in each quantity

[tex](4x^2+5x)+(8x+10)\\x(4x+5)+2(4x+5)[/tex]

Now group x+2 together

[tex](x+2)(4x+5)[/tex]

Finally, set each factor equal to 0 and solve for x

[tex]x+2=0\\x+2-2=0-2\\x=-2\\\\\\4x+5=0\\4x+5-5=0-5\\4x=-5\\\frac{4x}{4} =\frac{-5}{4} \\x=-\frac{5}{4}[/tex]

Dexter makes 40 cookies.
He eats 16 of the cookies and take the rest to school.
What percentage of the cookies does he take to school?

Answers

24 because you just have to some simple things to be what it turns out to be

25:50=4x:8. What is the value of X​

Answers

Answer: X = 1

Step-by-step explanation:

25/50 = 4x/8

First, multiply both sides by 8, therefore, the 8 on the right side will be canceled out.

25*8/50 = 4x*8/8

25*8/50 = 4x

25*8 = 200

200 divided by 50 = 4

4 = 4x

After that, you just need to divide 4 on both sides, therefore, the 4 on the right side will cancel out.

4/4 = 4x/4

1 = x

X = 1

Hope I helped! :]

Elias Rubio deposits three checks for $598.20, $2,274.26, and $3,248.79.
His cash consists of 75 one dollar bills, 78 five dollar bill., 83 ten-dollar
bills, 80 quarters, 32 dimes, 95 nickels, and. 5 pennies. He would like to
receive $40.00 in cash.

Answers

Based on the amount of cash that Elias Rubio brings, we can calculate that his total cash deposit is $1,323

How much did Elias deposit in cash?

This can be found as:

= (75 x 1) + (78 x 5) + (83 x 10) + (80 x 0.25) + (32 x 0.10 or 10 cents) + (95 x 0.05 or 5 cents) + (5 x 0.01 or 1 cent)

Solving gives:

= 75 + 390 + 830 + 20 + 3.20 + 4.75 + 0.05

= $1,323

Remaining part of the question:

How much did he deposit in cash?

Find out more on cash deposits at https://brainly.com/question/25803059.

#SPJ1

Which of the following is equivalent to √?
O
2
√2
O 2√2
2+√√√2

Answers

Answer:

2 sqrt(2)

Step-by-step explanation:

To simplify a square root

sqrt(8)

sqrt(4*2)

sqrt(4) sqrt(2)

2 sqrt(2)

Answer:

2√2

Step-by-step explanation:

√8 =[tex]\sqrt{4 \times 2}[/tex]

= 2√2 (√4 = 2)

Hence, 2√2 is the required answer.

A competition to catch the most rainbow trout on Lake Rainbow pitched the men against the ladies. 16 men and 12 women participated. Each participant had a total of 15 attempts before they retired from the competition. It was predicted that the men would have a 9% chance of catching a rainbow trout at each attempt. One participant's experience resulted in 3 successful catches. The probability that this participant was a woman is 40%. Find the probability that a participant successfully catches 3 rainbow trout, given that the participant was a woman.

Answers

The probability that a participant successfully catches 3 rainbow trout, given that the participant was a woman is 0.0042.

P(woman) = 12/28

= 3/7

P(men) = 16/28

= 4/7

P(3 trouts) = P(3 trout | women)*P(woman) + P(3 trout | men)*P(man)

= P(3 trout | women)*(3/7) + (15C3 * (0.09^3)*(1-0.09)^(15*3))*(4/7)

= P(3 trout | women)*(3/7) + (0.00476)*(4/7)

P(woman | 3 trout) = P(3 trout | women)*P(woman) / P(3 trouts)

{P(3 trout | women) = p}

p*(3/7) / (p*(3/7) + (0.00476)*(4/7)) = 0.40

p*(3/7)/0.40 = (p*(3/7) + (0.00476)*(4/7))

p*((3/7)/0.40 - (3/7)) = (0.00476)*(4/7)

p = [(0.00476)*(4/7)] / [((3/7)/0.40 - (3/7))]

= 0.0042

Learn more about probability here https://brainly.com/question/24756209

#SPJ4

In a factory, the chance that a certain machine works without overheating in the morning is 50%. if it runs smoothly all morning, then there is an 85% chance that it will continue for the rest of the day and a 15% chance that it will stop due to overheating. what is the probability that on a given day it will work in the morning and overheat later on? a. 4% b. 3.75% c. 7.5% d. 3.5%

Answers

Answer: C. 7.5%

Solve as decimal

0.5*0.15=0.075

Move two decimal points over

0.075 -> 7.5

Change back to percent

7.5%

Solve the following inequalities and represent the solution on the number line.
d) 5x ≥ 15
e) 3(2x + 1) ≤ 15

Answers

d) 5x ≥ 15

Let's solve your inequality step-by-step.

5x≥15

Step 1: Divide both sides by 5.

[tex]\frac{5x}{5} \geq \frac{15}{5}[/tex]

[tex]x\geq 3[/tex]

(Attachment #1)

e) 3(2x + 1) ≤ 15

Let's solve your inequality step-by-step.

3(2x+1)≤15

Step 1: Simplify both sides of the inequality.

6x+3≤15

Step 2: Subtract 3 from both sides.

6x+3−3≤15−3

6x≤12

Step 3: Divide both sides by 6.

[tex]\frac{6x}{6} \leq \frac{12}{6}[/tex]

[tex]x\leq 2[/tex]

(Attachment #2)


5(2x - 12) + 21 = 2x + 41
05
08
O 10
072

Answers

Answer:

x = 10

Step-by-step explanation:

5(2x - 12) + 21 = 2x + 41 ← distribute parenthesis and simplify left side

10x - 60 + 21 = 2x + 41

10x - 39 = 2x + 41 ( subtract 2x from both sides )

8x - 39 = 41 ( add 39 to both sides )

8x = 80 ( divide both sides by 8 )

x = 10

If the bearing of p from y is 048degrees what is the bearing of y from p

Answers

Step-by-step explanation:

see photo for detailed analysis


2. Compare and contrast a function and its inverse. Represent your
answer in a table of values and in a mapping diagram.

Answers

The table of values for the comparison of a function and its inverse function is shown in the image attached below.

What is an inverse function?

An inverse function refers to a type of function that is obtained by reversing the operation of a given function (f(x)).

In Mathematics, a given function (f(x)) and its inverse function has the following property f⁻¹(f(x)) = x. By applying this property to the table (see attachment), we have:

f(-6) = -10f⁻¹(-10) = -6f⁻¹(f(3)) = -9.

Read more on inverse function here: https://brainly.com/question/15635761

#SPJ1

Please help me i would really appreciate it, worth 11 points

Answers

The number of seconds it takes for the waste to hit the ground for the given function is: 5 seconds.

How to Evaluate a Function?

We are given the function of height to time as, h(t) = -16t² + initial height, and we have the following:

h(t) = 0 (height of the ground is 0)t = seconds the waste takes to height the groundInitial height = 400 feet

Plug in the values into the equation of the function

0 = -16t² + 400

Solve for t

0 - 400 = -16t²

-400 = -16t²

-400/-16 = t²

400/16 = t²

√(400/16) = t

20/4 = t

5 = t

t = 5

The number of seconds it takes is: 5 seconds.

Learn more about functions on:

https://brainly.com/question/10439235

#SPJ1

Given a function f : a → b and a subset y ⊆ b, is f (f −1 (y)) = y always true? prove or give a counterexample

Answers

If the subset y is the empty set, then the statement is false. That is the counterexample.

Is the statement true?

We know that for an invertible function, we always have that:

[tex]f(x) = y\\f^{-1}(y) = x[/tex]

Now, the range of f(x) is the set b. This means that the domain of the inverse is the set b. Such that:

f^{-1} is defined on b→a

Now we want to work on a subset y ⊆ b.

And here comes the problem.

The empty set {∅} is a subset of ay other set. So, if y is the empty set, there are no elements where we can evaluate the inverse function. From that counterexample, we conclude that the statement is false.

If you want to learn more about inverse functions:

https://brainly.com/question/14899241

#SPJ12

Dry concrete can be made by mixing sand, gravel and cement
in the ratio 1: 2: 3. If you want 1800 kg of dry concrete,
how much of each will you need? Give your answers in
kilograms (kg).

Answers

Sand is 1/6 of the mixture. 1/6 x 1800 = 300 kg
Gravel is 2/6 of mixture. 2/6 x 1800 = 600 kg
Cement is 3/6 of mixture. 3/6 x 1800 = 900 kg

A ratio shows how many times one number contains another.

Hence, the sand is in the ratio [tex]\frac{1}{6}[/tex] of the mixture is

[tex]\frac{1}{6}[/tex]×[tex]1800=300kg[/tex]

The Gravel is in the ratio [tex]\frac{2}{6}[/tex]×[tex]1800=600kg[/tex]

And the cement is in ratio [tex]\frac{3}{6}[/tex]×[tex]1800=900kg[/tex]

What is the ratio ?

A ratio is an ordered pair of numbers [tex]a[/tex] and [tex]b[/tex], written [tex]\frac{a}{b}[/tex] where [tex]b[/tex] does not equal [tex]0[/tex]. A proportion is an equation in which two ratios are set equal to each other.

Here the given ratio is [tex]1:2:3[/tex].

Here given that,

The dry concrete is   [tex]1800kg[/tex].

And the multiplication of the ratio is [tex]1[/tex]×[tex]2[/tex]×[tex]3=6[/tex]

Hence, the sand is in the ratio [tex]\frac{1}{6}[/tex] of the mixture is

[tex]\frac{1}{6}[/tex]×[tex]1800=300kg[/tex]

The Gravel is in the ratio [tex]\frac{2}{6}[/tex]×[tex]1800=600kg[/tex]

And the cement is in ratio [tex]\frac{3}{6}[/tex]×[tex]1800=900kg[/tex]

To know more about the ratio

https://brainly.com/question/23499990

#SPJ2

Mike has 63 toys. 18 of them are new and 12 are his favorites, while 4 are new and favorites. Mike is giving away all the toys that are neither new nor favorites. How many toys does mike have? ASAp

Answers

Answer:34

Step-by-step explanation:

Giving away all that is not new or fav so 12 fav + 18 new + 4 which are new an favorite = 34

Answer:

22

Step-by-step explanation:

63 is the total

14 are new

8 are fav

14+8=22

Vertex A in quadrilateral ABCD lies at (-3, 2). If you rotate ABCD 180° clockwise about the origin, what will be the coordinates of A′ of the rotated quadrilateral A′B′C′D′?

Answers

The answer is the letter

A

Select the correct answer.
As part of a community-service project, a local club has decided to paint 864 walls across town. The club has 36 volunteers. If the work is divided evenly, how many walls must each volunteer paint?

A.
24
B.
29
C.
34
D.
39

Answers

The 24 walls must paint by each volunteer if the work is divided evenly and the club has 36 volunteers.

What is a fraction?

Fraction number consists of two parts, one is the top of the fraction number which is called the numerator and the second is the bottom of the fraction number which is called the denominator.

We have:

As part of a community-service project, a local club has decided to paint 864 walls across town. The club has 36 volunteers.

Total number of volunteers = 36

Number of walls = 864

The number of walls each volunteer paint can be expressed as a fraction:

= 864/36

= 24

Thus, the 24 walls must paint by each volunteer if the work is divided evenly and the club has 36 volunteers.

Learn more about the fraction here:

brainly.com/question/1301963

#SPJ1

What is the greatest area of a rectangle with a perimeter of 60cm? What is the length and width of this rectangle?

Answers

The length and width of this rectangle are 15 cm respectively

How to determine the greatest area?

The perimeter is given as:

Perimeter, P = 60

The greatest area is calculated as:

Greatest = (P/4)^2

Substitute 60 for P

Greatest = (60/4)^2

Evaluate the quotient

Greatest = 15^2

Evaluate the exponent

Greatest = 225 square centimeters

Hence, the greatest area is 225 square centimeters

How to determine the length and width

We understand that the area is the greatest.

In such a scenario;

Length = Width

This means that:

Area =Length^2 =Width^2

So, we have:

Length^2 =Width^2 = 225

Take the square root

Length =Width = 15

Hence, the length and width of this rectangle are 15 cm respectively

Read more about areas at:

https://brainly.com/question/24487155

#SPJ1

1
2 3
4
5
6
7
8
9 10
Which set of angle measures could be the measures of the interior angles of a triangle?
O 90°, 42°, and 58°
O 60°, 60°, and 60°
O 100°, 48°, and 42°
O 31°, 75°, and 70°
TIME REMAI
42:34

Answers

Answer:

1) -
2) +

3) -
4) +

Step-by-step explanation:

сумма внутренних углов треугольника не должна превышать 180 градусов

Bilquis wants to ride her bicycle 47.6 miles this week. She has already ridden 8 miles. If she rides for 6 more days, what is the average number of miles she would have to ride each day to meet her goal?

Answers

If she rides for 6 more days, what is the average number of miles she would have to ride each day to meet her goal is 4.7

We have given that,

Bilquis wants to ride her bicycle 47.6 miles this week. She has already ridden 8 miles.

We have to determine that If she rides for 6 more days, what is the average number of miles she would have to ride each day to meet her goal.

Based on the given conditions, formulate: 8+4x=26

Rearrange unknown terms to the left side of the equation:4x=26-8

Calculate the sum or difference:4x=18

Divide both sides of the equation by the coefficient of the variable:4x/4=18/4

Calculate the product or quotient:x=18/4

We get the result:4.7

To learn more about the equation visit:

https://brainly.ph/question/25003

#SPJ1

Answer: The answer is 6.6

Step-by-step explanation:

3. Choose the equation that correctly shows the Commutative Property of Multiplication. 5 × 1 3 = 1 3 ÷ 5 5 × 1 3 = 5 × 1 3 5 + 1 3 = 1 3 × 5

Answers

According to the commutative property of multiplication, changing the order of components has no effect on the product. The correct option is B.

What is the commutative property of multiplication?

According to the commutative property of multiplication, changing the order of components has no effect on the product.

For example: 4 × 8 = 8 × 4 = 32

The equation that correctly shows the Commutative Property of Multiplication is,

5 × 1 3 = 5 × 1 3

Hence, the correct option is B.

Learn more about the Commutative Property of multiplication:

https://brainly.com/question/14391436

#SPJ1

3. What mathematical symbol is appropriate to use given the
word?
4. What word is appropriate to use given the symbol?

Answers

Answer:

X

Step-by-step explanation:

Given: cot = -0.59 in QII, find sin

Answers

The value of sin x in Q II is 0.86 .

What are Trigonometry ?

This the field in Maths which deals with a right angled triangle and the other angles in the triangle.

It is given that cot = -0.59

cot x = cos x / sin x

Using online trigonometric calculator

sin x in Q II is 0.86 .

To know more about Trigonometry

https://brainly.com/question/26719838

#SPJ1

Find all real numbers $a$ that satisfy \[\frac{1}{a^3 + 7} -7 = \frac{-a^3}{a^3 + 7}.\]

Answers

The real number of the given expression is a=-2.

Given that the expression is [tex]\frac{1}{a^3+7}-7=\frac{-a^3}{a^3+7}[/tex]

Real numbers is known as the union of both rational and irrational numbers. Real numbers can be both positive or negative and are denoted by the symbol “R”.

To compute the value of a.

In the given expression multiply both sides with (a³+7) as

[tex]\frac{(a^3+7)}{a^3+7}-7=\frac{-a^3(a^3+7)}{a^3+7}[/tex]

Simplify the expression as,

1-7(a³+7)=-a³

Expand out terms of the left hand side

1-7a³-49=-a³

-7a³-48=-a³

Taking out minus common from both sides and cancel them

-(7a³+48)=-(a³)

7a³+48=a³

Add -a³-48 on both sides

7a³+48-a³-48=a³-a³-48

6a³=-48

Divide both sides with 6

(6÷6)a³=(-48÷6)

a³=-8

write -8 in the expansion form which is (-2)×(-2)×(-2)=-8

a³=(-2)³

From above it says that

a=-2

Hence, real number that satisfy [tex]\frac{1}{a^3+7}-7=\frac{-a^3}{a^3+7}[/tex] is a=-2.

Learn about real numbers from here brainly.com/question/10180279

#SPJ4

Using a standard deck of cards, find the probability of selecting a jack, replacing the card, and then selecting a king.

please explain

Answers

The probability of selecting a jack, replacing the card, and then selecting a king is 1/169

How to determine the probability?

In a standard deck of cards, we have:

Total = 52

Jack = 4

King = 4

The probability of each is:

P(Jack) = 4/52

P(King) = 4/52

So, we have:

P = 4/52 * 4/52

Simplify

P = 1/13 * 1/13

Evaluate

P = 1/169

Hence, the probability is 1/169

Read more about probability at:

https://brainly.com/question/25870256

#SPJ1

Other Questions
presenter selects multimedia materials primarily based on their abilitytoorganize data.distract the audience.introduce information.emphasize a point. Based on the audio, what food group does Martina seem to prefer? (1 point) There are 130 people in asport centre.73 people use thegym.62 people use the swimming pool.58 people use the track.22 people use the gym and the pool.29 people use the pool and the track.25 people use the gym and the track.11 people use all three facilities.A person is selected at random.What is the probability that thisperson doesn't use any facility? Describes howHIV viruses Progress in infected person Find the slope of the line silent letter in the word depot c. In what ways could you reduce your water usage if there was a water shortage? find the maxium value of 16x+ 96y What is the missing step in solving the inequality 4(x 3) + 4 < 10 + 6x? 1. The distributive property: 4x 12 + 4 < 10 + 6x 2. Combine like terms: 4x 8 < 10 + 6x 3. The addition property of inequality: 4x < 18 + 6x 4. The subtraction property of inequality: 2x < 18 5. The division property of inequality: ________ x < 9 x > 9 x < x is less than or equal to negative StartFraction 1 Over 9 EndFraction. x > x is greater than or equal to negative StartFraction 1 Over 9 EndFraction. A woman passed gas silently. I said "it stinks", and she said "I apologize. Excuse me". Why did she say both of those things? please answer me I will f0ll0w u which is the base class in the following statement? class car : public vehicle But, leathery hands fullof wet brown life,knee deep in the summerroadside grass,he just smiled and saidthey have places to go totoo.Birdfoots Grampa, Joseph BruchacWhat does the man mean when he says, they have places to go to too?He believes that all living things are important.The narrator has to go to school.He believes that the toads are in a hurry to get dry.The toads must go home with him and the narrator. AP Calculus AB Question from A, P .E* X(Will give branliest if correct) What is adaptive radiation?A. the evolution of two species from a single ancestor in a short amount of timeB. the evolution of many species from a single ancestor in a short amount of timeC. the evolution of many species from a single ancestor over a long period of timeD. the evolution of two species from a single ancestor over a long period of time Which of the following equations have exactly one solution?Choose all answers that apply: As robin uses her computer to write a report of her teams investigation she is struggling to keep the foot notes numbered in the correct order which of the following is the best advice for robin What net force is required to cause a 12,000 kg airplane to accelerate at a rate of 5.2 m/s March 8, 2017, one U.S. dollar was worth 66.79 Indian rupees.a) On that date, how many dollars was 110.66 rupees worth?Round your answer to the nearest hundredth of a dollar. I need help with this question. in what circumstance will 2023 leafs available intelligent driver alertness (i-da) provide audible and visual warnings?