We can observe that the first three terms, $x^2 + 2x + 1$, form a perfect square trinomial.
Recall the formula for a perfect square trinomial: $(a+b)^2 = a^2 + 2ab + b^2$.
In this case, if we let $a=x$ and $b=1$, then $a^2 + 2ab + b^2 = x^2 + 2(x)(1) + 1^2 = x^2 +
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