# How do you factor ab - a^4b?

You can factor out what both terms have in common, which is $a b$ multiplying each:
$a b \left(1 - {a}^{3}\right)$
To verify your factorizing is correct, one useful tip is to resort to the law of exponentials that states ${a}^{n} \cdot {a}^{m} = {a}^{n + m}$