Question

If y = (x + 3)2, then (-2x - 6)2 must equal which of the following?

A.
-4y2

B.
-2y2

C. -4y
D. 4y

wHAT FORMULA DO I USE TO GET THE ANSWER?

Answer 1

Does anyone know what formula I use to get the answer?

Answer 2

You use math...

\[y = (x+3)^2\]
\[\sqrt(y) = x+3\]
\[(-2x-6)^2 = (-2\sqrt(y))^2\]
=4y

(...gotta learn how to write latex again)

Answer 3

@nphuongsun93 Thank can you walk me through the steps so I know how to do it with other problems?

Answer 4

Ok.
\[y = (x+3)^2\]\[\sqrt(y) = x+3\] Understand this so far?

Answer 5

hint: \( y={\color{brown}{ (x+3)^2 }}\qquad (-2x-6)^2\to
\begin{cases}
[-2(x+3)]^2\impliedby \textit{common factor}\\
(-2)^2(x+3)^2\impliedby expanded\\
+4{\color{brown}{ (x+3)^2 }}
\end{cases}\)