Answer
$25x^2+40x+16$
Work Step by Step
A binomial squared is equal to the square of the first term plus or minus twice the product of both terms plus the square of the second term.
$(a + b)^2 = a^2 + 2ab + b^2$
$(5x+4)^2=(5x)^2+2(5x)(4)+4^2=25x^2+40x+16$
