Answer:
x² + 7x + 12
Explanation:
The area of a rectangle = length × width
here length = x + 4 and width = x + 3, hence
A = (x + 4)(x + 3)
Each term in the second parenthesis is multiplied by each term in the first parenthesis.
A = x(x + 3) + 4(x + 3) ← distribute each parenthesis
A = x² + 3x + 4x + 12 ← collect like terms
A = x² + 7x + 12 ← in standard form