Answer:
x³ - 3x² - 13x + 15
Step-by-step explanation:
Each term in the second factor is multiplied by each term in the first factor, that is
x(x² - 6x + 5) + 3(x² - 6x + 5) ← distribute both parenthesis
= x³ - 6x² + 5x + 3x² - 18x + 15 ← collect like terms
= x³ - 3x² - 13x + 15
