Answer
$(a+9)(a-7)$
Work Step by Step
$a^2+2a-63$ has no common monomial factors.
=$(\ \ \ \ \ \ \ \ \ )(\ \ \ \ \ \ \ \ \ )$
=$(a\ \ \ \ \ \ \ )(a\ \ \ \ \ \ \ )$
=$(a+\ \ )(a-\ \ )$ The factors of -63 must have dislike signs.
=$(a+9)(a-7)$ -7 and 9 have a sum of 2 and a product of -63.
