Answer
$x^{2}-10x+25$
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 $(A-B)^{2}=A^{2}-2AB+B^{2}$
$(x-5)^{2}=x^{2}-2\cdot x\cdot 5+5^{2}$
= $x^{2}-10x+25$
