Y ∝ √ x If y = 42 when x = 9 find, y when x = 100

y = 140

Step-by-step explanation:

Given y varies directly with then the equation relating them is

y = k ← k is the constant of variation

To find k use the condition y = 42 when x = 9 , then

42 = k = 3k ( divide both sides by 3 )

14 = k

y = 14 ← equation of variation

When x = 100 , then

y = 14 × = 14 × 10 = 140

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer