Which of the following equations is not equivalent to 36y^2 + 9 = x^2?

Question

Which of the following equations is not equivalent to  36y^2 + 9 = x^2 ?

(A)  36y^2 = x^2 - 9

(B)  36y^2 = (x - 3)(x + 3)

(C)  108y^2 + 27 = 3x^2

(D)  y^2 = \frac{x^2 - 9}{36}

(E)  6y = x - 3

Jashan79 · Answer

E because squaring both sides won't give the desired equation.

Adityagmatclub · Answer

Just rearrange other equation to equation mention in the question. You will get the answer. I must say worse question on GMATclub.

E does not belong to the group.

Plunkster82 · Answer

I went with E and I tried to go so slow so as not to make a simple mistake.

E gave me some pause, because the square root of 36y^2 is 6y. However, the square root of x^2-9 isn't x-3. So that's what sealed it for me.

I wasted time on the earlier answers and just needed to stay calm, focus and not make stupid mistake.

Siva2021 · Answer

IMO Option E
On squaring both sides won't give the equation.
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