Answer:
y² + 8y + 16
Explanation:
Given
(y + 4)²
= (y + 4)(y + 4)
Each term in the second parenthesis is multiplied by each term in the first parenthesis, that is
y(y + 4) + 4(y + 4) ← distribute both parenthesis
= y² + 4y + 4y + 16 ← collect like terms
= y² + 8y + 16