Question

If y varies directly as x, and y = 15 as x = -3, find y for the x-value of 4.

Answer 1

y = kx where k is the constant of variation

the first step is to find the value of k by substituting values for x and y. These are x = -3 and y = 15. Can you do that?

Answer 2

y = kx is direct variation.

Answer 3

would it be.... x=-20?

Answer 4

I'll start you off

y = k x

15 = k* -3

tofind k we divide both sides of the equation by -3.

Answer 5

-3/15=4/x is the first step right?

Answer 6

if it varies directly, u can set it up as a proportion

Answer 7

yes - you can do it that way

Answer 8

-20 is correct

Answer 9

I wish I could give you more medals :(

Answer 10

thats OK
yw

Answer 11

not that k is -5

so if x = 4

y = -5*4 = -20

Answer 12

You're awesome! no wonder you're the honorary professor