Chapter 10 - Section 10.4 - Adding, Subtracting, and Multiplying Radical Expressions - Exercise Set - Page 710: 55

$(\sqrt[3]{a}-4)(\sqrt[3]{a}+5)=\sqrt[3]{a^{2}}+\sqrt[3]{a}-20$

$(\sqrt[3]{a}-4)(\sqrt[3]{a}+5)$ Evaluate the product: $(\sqrt[3]{a}-4)(\sqrt[3]{a}+5)=\sqrt[3]{a^{2}}+5\sqrt[3]{a}-4\sqrt[3]{a}-20=...$ Now, simplify by combining like terms: $...=\sqrt[3]{a^{2}}+(5-4)\sqrt[3]{a}-20=\sqrt[3]{a^{2}}+\sqrt[3]{a}-20$