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GMAT - Problem Solving - Algebra

Which of the following equations is NOT equivalent to 10y^2=(x+2)(x?2) ?

Which of the following equations is NOT equivalent to 10y2=(x 2)(x2) ?


(A) 30y2=3x212

(B) 20y2=(2x4)(x 2)

(C) 10y2 4=x2

(D) 5y2=x22

(E) y2=(x24)/10

Analysing Options:

A. 30y2=3x212

dividing both sides by 3

10y2 = x2 - 4 = (x + 2) (x - 2)

Equivalent

(B) 20y2=(2x4)(x+2)

20y2 = 2(x - 2) (x + 2)

dividing both sides by 2

10y2 = (x - 2) (x + 2)

Equivalent

(C) 10y2+4=x2

10y2 = x2 - 4 = (x + 2) (x - 2)

Equivalent

(D) 5y2=x22

Not equivalent

(E) y2=(x24)/10

10y2 = x2 - 4 = (x + 2) (x - 2)