Question

The table below shows values for x and y. If y varies directly as x, what is the constant of variation?

x y
0 0
1 -9
2 -18
3 -27




-9

0

3

9

Answer 1

-9.

Explanation:

y varies directly as x so y = kx where k is the constant of variation.

Inserting the values of x and y.

0 = k*0

-9 = k*1 so k = -9

-18 = 2*k so k = -9

-27 = 3 *k so k = -9.

Answer 2

k = - 9

Explanation:

Given that y varies directly as x then the equation relating them is

y = kx ← k is the constant of variation

To find k use any ordered pair from the given table of values

Using x = 1, y = - 9, then

k =
`(y)/(x)` =
`(-9)/(1)` = - 9