Question

If y varies directly as x and y=9 when x=-3, find y when x=18....
Please show steps on how you did it :)

Answer 1

y varies directly as x

means that

y = k*x

where k is some fixed number

Answer 2

it tells us that when x =-3, y = 9, so this means

y = k*x

9 = k*(-3)

k = ???

Answer 3

what did you get for k

Answer 4

k=-3

Answer 5

is that right?

Answer 6

yes it is

Answer 7

since k = -3 and y = kx, we can say that the equation is y = -3x

Answer 8

when x = 18, what is y?

Answer 9

-54

Answer 10

good

Answer 11

thank you

Answer 12

you're welcome