Question

If y= 4, x=2. Find y when x = 1

Answer 1

y = 32

Explanation:

Given y is inversely proportional to the cube of x then the equation relating them is

y =
`(k)/(x^3)` ← k is the constant of proportionality

To find k use the condition y = 4, x = 2, then

4 =
`(k)/(2^3)` =
`(k)/(8)` ( multiply both sides by 8 )

32 = k, thus

y =
`(32)/(x^3)` ← proportional equation

When x = 1, then

y =
`(32)/(1^3)` =
`(32)/(1)` = 32