Answer:
4x³ + x² - 20x - 5
Step-by-step explanation:
Calculate f(x) × g(x), that is
(4x + 1)(x² - 5)
Each term in the second factor is multiplied by each term in the first factor, that is
4x(x² - 5) + 1(x² - 5) ← distribute both parenthesis
= 4x³ - 20x + x² - 5
= 4x³ + x² - 20x - 5 ← in standard form