Question

If the value of “y” varies directly with “x” and y = -1 when x = 3 find “y” if x = 9

Answer 1

Answer:

y = - 3

Step-by-step explanation:

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

y = kx ← k is the constant of variation

To find k use the condition y = - 1 when x = 3

k = $\frac{y}{x}$ = $\frac{-1}{3}$ = - $\frac{1}{3}$

y = - $\frac{1}{3}$ x ← equation of variation

When x = 9, then

y = - $\frac{1}{3}$ × 9 = - 3