Question

factor by any method.
$a^2 - 7a + ab - 7b$

Explanation:

Step1: Group terms into pairs

Group first two and last two terms:
$(a^2 - 7a) + (ab - 7b)$

Step2: Factor out GCF from each group

Factor $a$ from first group, $b$ from second:
$a(a - 7) + b(a - 7)$

Step3: Factor out common binomial

Factor out $(a - 7)$ from both terms:
$(a - 7)(a + b)$

Answer:

$\boldsymbol{(a - 7)(a + b)}$