Question

Y is inversely proportional to V1+x.
When x = 8, y = 2.
Find y when x = 15.

Answer 1

y = 1.5

Explanation:

Given x is inversely proportional to
`√(1+x)` , then the equation relating them is

y =
`(k)/(√(1+x) )` ← k is the constant of proportion

To find k use the condition when x = 8, y = 2

2 =
`(k)/(√(1+8) )` =
`(k)/(√(9) )` =
`(k)/(3)` ( multiply both sides by 3 )

6 = k

y =
`(6)/(√(1+x) )` ← equation of proportion

When x = 15 , then

y =
`(6)/(√(1+15) )` =
`(6)/(√(16) )` =
`(6)/(4)` =
`(3)/(2)` = 1.5