Question: Divide:
x4 − y4 by x2 − y2
Solution:
$\frac{x^{4}-y^{4}}{x^{2}-y^{2}}$
$=\frac{\left(x^{2}\right)^{2}-\left(y^{2}\right)^{2}}{\left(x^{2}-y^{2}\right)}$
$=\frac{\left(x^{2}+y^{2}\right)\left(x^{2}-y^{2}\right)}{\left(x^{2}-y^{2}\right)}$
$=x^{2}+y^{2}$
