## Elementary Algebra

$16x^2-40x+25$
Using $(a+b)^2=a^2+2ab+b^2$, or the square of a binomial, the given expression, $(4x-5)^2 ,$ is equivalent to \begin{array}{l}\require{cancel} (4x)^2+2(4x)(-5)+(-5)^2 \\\\= 16x^2-40x+25 .\end{array}