## Calculus with Applications (10th Edition)

$$4b^2$$
Factor the terms inside the radical $$\sqrt[3]{64b^6}=\sqrt[3]{2^6b^6}=\sqrt[3]{2^32^3b^3b^3}$$ The cube root of a cubed expression is the expression $$=2\times 2 \times b\times b=4b^2$$