Question

If f(x) varies directly with x and f(x) = 3 when x = 12, then what is the value of f(x) when x = 40?
480
160
10
4

Answer 1

The formula for direct variation is y(or f(x)=kx. So plug in what you know into that equation and solve for k. Now that you know k, plug in what you know into f(x)=kx and you can solve for f(x).

Answer 2

So f(x)=12(40)

Answer 3

3=k(12)
3/12=k 1/4=k
f(x)=1/4(40)
f(x)=10

Answer 4

First you solve for k. Then with the second set of numbers find f(x) now that you know what k is

Answer 5

Do you get it?

Answer 6

Kinda of thanks

Answer 7

so the answer is d?"

Answer 8

It would be 10

Answer 9

Do u have another practice problem?

Answer 10

Yes :P

Answer 11

Given the function T(z) = 7 – z, find T(–4).
–11
11
-3
3

Answer 12

Is that \[t(z)=7-z\]

Answer 13

Since it gives you T(z) is -4, you would just plug that in.
-4=7-z Subtract the 7
-11=z

Answer 14

oh

Answer 15

Is that what you were thinking?

Answer 16

Yes