Question

Simplify (x-y)^2 / x^3-y^3

Answer 1

Recall the identity $a^3-b^3=(a-b)(a^2+ab+b^2)$

The given expression is same as
$\dfrac{(x-y)^2}{(x-y)(x^2+xy+y^2)}$

Cancel the common factor $x-y$ top and bottom and get
$\dfrac{x-y}{x^2+xy+y^2}$

Answer 2

=x^2+y^2-2xy/x^3-y^3
=-2