Answer
$x^{2}+8x+16$
Work Step by Step
The standard form of a polynomial is
$a_{n}x^{n}+a_{n}x^{n-1}+\cdots+a_{1}x+a_{0}$
(written in order, highest degree first. If a term is missing, it means that the coefficient is 0)
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Use the perfect square formula $(A+B)^{2}=A^{2}+2AB+B^{2}$
$(x+4)^{2}=x^{2}+2\cdot x\cdot 4+4^{2}$
= $x^{2}+8x+16$
