## Intermediate Algebra (6th Edition)

b., $x^{2}-49$
$(x+7)(x-7)$ As shown on page 286, the product of the sum and difference of a two terms is given by the following formula: $(a+b)(a-b)=a^{2}-b^{2}$ In this case, $a=x$ and $b=7$. $(x+7)(x-7)=x^{2}-7^{2}=x^{2}-49$