## Precalculus (6th Edition) Blitzer

$x^{4}+4x^{2}+4$
... expand the square of the sum with $(a+b)^{2}=a^{2}+2ab+b^{2}$ $(x^{2}+2)^{2}=(x^{2})^{2}+2(x^{2})(2)+(2)^{2}\quad$... use the rule: $(a^{m})^{n}=a^{mn}$ = $x^{4}+4x^{2}+4$