Question

Suppose y varies directly with x and y=12 when x=-3 what is the value of y when x=6?

A. -24
B. 2
C. -2
D. -4

Answer 1

A. -24

Explanation:

we know that

A relationship between two variables, x, and y, represent a directly or proportional variation if it can be expressed in the form
`k=(y)/(x)` or
`y=kx`

In this problem we have

For x=-3, y=12

Find the value of the constant of proportionality k

`k=(y)/(x)`

substitute the given values

`k=(12)/(-3)=-4`

so

The linear equation is equal to

`y=-4x`

what is the value of y when x=6?

substitute the value of x in the linear equation and solve for y

`y=-4(6)=-24`