All categories

2 years ago

It is given that A is directly proportional to r2 and r> 0. When r=5, A=75.

Mathematics

1 answer:

torisob [31]2 years ago

3 0

Answer:

see explanation

Step-by-step explanation:

Given A is directly proportional to r² then the equation relating them is

A = kr² ← k is the constant of proportion

To find k use the condition when r = 5, A = 75 , then

75 = k × 5² = 25k ( divide both sides by 25 )

3 = k

A = 3r² ← equation of proportion

(a)

when r = 4, then

A = 3 × 4² = 3 × 16 = 48

(b)

when A = 147 , then

147 = 3r² ( divide both sides by 3 )

49 = r² ( take the square root of both sides )

r = $\sqrt{49}$ = 7

You might be interested in

Kevin just bought a refrigerator for 469. He paid 140.60 in a down payment and will pay the rest in equal installments. How much

enyata [817]

Answer:

$54.73 monthly installment for 6 months.

Step-by-step explanation:

Kevin just bought a refrigerator for $469.

He paid $140.6 in down payment and will pay the rest in equal installments.

If Kevin does not have to pay any interest and he will pay the rest amount in 6 months with monthly installments,

Then, the value of each installment will be = $\frac{469 - 140.60}{6} = 54.73$ Dollars. (Answer)

4 0

2 years ago

Y=25000(1-0.63)^2<br> Find the decay rate.

Anestetic [448]

If I'm not mistaken.. the half-life should be 40,750 years.. so

y = 40,750

I got this by multiplying 25,000 by 1.63 and then if you divide by 2.. you get

20,375.. so one of those should be correct

4 0

2 years ago

Without sketching the graph, find the x intercepts and y-intercepts of the graph of the equation 2x+3y=12 What isjare the x-inte

den301095 [7]

Answer:

x-intercept: (6,0)

y-intercept: (0,4)

Step-by-step explanation:

The x-intercepts lay on the x-axis and therefore their y-coordinate is 0.

To find the x-intercept, you set y to 0 and solve for x.

2x+3y=12

Set y=0.

2x+3(0)=12

2x+0 =12

2x =12

Divide both sides by 2:

x =12/2

x =6

The x-intercept is (x,y)=(6,0).

The y-intercepts lay on the y-axis and therefore their x-coordinate is 0.

To find the y-intercept, you set x to 0 solve for y.

2x+3y=12

2(0)+3y=12

0+3y =12

3y =12

Divide both sides by 3:

y =12/3

y =4

The y-intercept is (0,4).

8 0

2 years ago

How do you work out 9/10 divided by 6/7??

Helga [31]

$\frac{9}{10} \div \frac{6}{7}$
You just flip 6/7 so it would be 7/6 and then you times it.
$\frac{9}{10} \div \frac{6}{7}$
$\frac{9}{10} \times \frac{7}{6} = \frac{63}{60} = \frac{21}{20}$

6 0

2 years ago

What is the simplified form of 12z^2-7z-12/3z^2+2z-8? ...?

gavmur [86]

It should go like this:

(4z + 3) (3z - 4) / (3z - 4) (z + 2)

Then you just cancel out (3z -4) and (3z -4), and the final simplified form of this polynomial is:

(4z +3) / (z + 2)

4 0

3 years ago