Question

If xy = 4, which is equivalent to y(x-4)(x+2)

Answer 1

4x - 8 - 32/x

Explanation:

From the expression xy = 4, y = 4/x

Substituting y = 4/x into the expression y(x-4)(x+2) and expanding;

= y(x-4)(x+2)

= 4/x(x-4)(x+2)

On expansion;

= (4-16/x)(x+2)

= 4x+4(2)-(16/x)x-(16/x)2

= 4x+8-16-32/x

= 4x-8-32/x

The equivalent expression is 4x - 8 - 32/x