Question

(-3y - 1)^2

Explanation:

Step1: Rewrite as squared sum

$(-3y-1)^2 = (-(3y+1))^2 = (3y+1)^2$

Step2: Apply square of sum formula

Recall $(a+b)^2 = a^2 + 2ab + b^2$, let $a=3y$, $b=1$:

$$\begin{align*} (3y+1)^2&=(3y)^2 + 2\times3y\times1 + 1^2\\ &=9y^2 + 6y + 1 \end{align*}$$

Answer:

$9y^2 + 6y + 1$