## Introductory Algebra for College Students (7th Edition)

$(x-7)^2$
RECALL: A perfect square trinomial can be factored using either of the following formulas: (i) $a^2+2ab+b^2= (a+b)^2$ (ii) $a^2-2ab+b^2=(a-b)^2$ The given perfect square trinomial can be written as: $=x^2- 2(x)(7) + 7^2$ This trinomial has the same form as the perfect square trinomial in formula (ii) above. Factor using formula (ii) with $a=x$ and $b=7$ to obtain: $=(x-7)^2$