Question

15(x + 3)²

Explanation:

Step1: Expand the squared binomial

Use the formula $(a+b)^2 = a^2 + 2ab + b^2$ where $a=x$, $b=3$:
$$(x+3)^2 = x^2 + 6x + 9$$

Step2: Distribute the 15 to each term

Multiply each term in the expanded binomial by 15:
$$15(x^2 + 6x + 9) = 15x^2 + 90x + 135$$

Answer:

$15x^2 + 90x + 135$