## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$a^2-\dfrac{4}{5}a+\dfrac{4}{25}$
Using $(a+b)^2=a^2+2ab+b^2$ or the square of a binomial, the given expression, $\left( a-\dfrac{2}{5} \right)^2$, is equivalent to \begin{array}{l}\require{cancel} (a)^2+2(a)\left( -\dfrac{2}{5} \right)+\left( -\dfrac{2}{5} \right)^2 \\\\= a^2-\dfrac{4}{5}a+\dfrac{4}{25} .\end{array}