## Precalculus: Mathematics for Calculus, 7th Edition

$a-b^{2}$
Change square roots into exponents: $(a^{1/2}-b)(a^{1/2}+b)$ Use the rule $(A+B)(A-B)=A^{2}-B^{2}$ to multiply. $a^{1/2}a^{1/2}-b^{2}$ Simplify: $a-b^{2}$