Answer:
- x³ - 15x² - 61x - 36
Explanation:
Given
(x² - 5x - 4)(x² + 4x + 9)
Each term in the second factor is multiplied by each term in the first factor, that is
x²(x² + 4x + 9) - 5x(x² + 4x + 9) - 4(x² + 4x + 9) ← distribute parenthesis
=
+ 4x³ + 9x² - 5x³ - 20x² - 45x - 4x² - 16x - 36 ← collect like terms
=
- x³ - 15x² - 61x - 36