Question

. If y varies directly with x when y = -4 and x = 10, determine y when x = 2. Write and equation for the direct variation and determine the value.

Answer 1

y = - 0.8

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 when y = - 4, x = 10, then

- 4 = 10k ( divide both sides by 10 )

- 0.4 = k

y = - 0.4x ← equation of variation

When x = 2 , then

y = - 0.4 × 2 = - 0.8