Question

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

Answer 1

y = 140

Explanation:

Given y varies directly with
`√(x)` then the equation relating them is

y = k
`√(x)` ← k is the constant of variation

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

42 = k
`√(9)` = 3k ( divide both sides by 3 )

14 = k

y = 14
`√(x)` ← equation of variation

When x = 100 , then

y = 14 ×
`√(100)` = 14 × 10 = 140