Question

The value of y varies directly as x and y is -15 when x is 5 what is the value of y when x=-3​

Answer 1

y = 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 the condition y = - 15 when x = 5, thus

k =
`(y)/(x)` =
`(-15)/(5)` = - 3

y = -3x ← equation of variation

When x = - 3, then

y = - 3(- 3) = 9