Introductory Algebra for College Students (7th Edition)

$x^4+4x^2+4$
Using $(a\pm b)^2=a^2\pm2ab+b^2$ or the square of a binomial, the square of the given expression, $\left( x^2+2 \right)^2,$ is \begin{array}{l}\require{cancel} (x^2)^2+2(x^2)(2)+(2)^2 \\\\= x^4+4x^2+4 .\end{array}