Answer:
[tex]x^{4}[/tex] - x³ - 15x² - 61x - 36
Step-by-step 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
= [tex]x^{4}[/tex] + 4x³ + 9x² - 5x³ - 20x² - 45x - 4x² - 16x - 36 ← collect like terms
= [tex]x^{4}[/tex] - x³ - 15x² - 61x - 36
