Question

The variable z varies jointly with the square of x and inversely with y. Z = 4.4 when x = 3 and y =2. Find an equation that relates the variables.

Answer 1

z = 0.9778x^2 / y.

Explanation:

When z varies with the square of x the equation is z = kx^2 where k = a constant.

If it also varies inversely with y the equation is z = kx^2/y.

When z = 4.4 , x = 3 and y = 2 we have:-

4.4 = k * 3^2 / 2

Multiplying by 2:

8.8 = 9k

k = 8.8 / 9

= 0.9778.

So the required formula is z = 0.9778x^2 / y.