Answer:
x² + 4x + 3
Step-by-step explanation:
Given
(x + 1)(x + 3)
Each term in the second factor is multiplied by each term in the first factor, that is
x(x + 3) + 1(x + 3) ← distribute both parenthesis
= x² + 3x + x + 3 ← collect like terms
= x² + 4x + 3
