Question from Gmat Prep software

[Prashantbhardwaj]

I couldn't reach a logical explanation regarding the answer for this question, So please help

If xy + z = x ( y + z ),
then which of the following must be true?

A) x=0 and z=0

B) x=1 and y=1

C) y=1 and z=0

D) x=1 or y=0

E) x=1 or z=0

[kmittal82]

I think the answer should be (E)

Expand the equation and compare the co-efficients:

xy + z = xy + xz

=> xz = z
=> xz- z = 0
=> z(x-1) = 0

=> either x = 1 Or z = 0

Can you please confirm the OA ?

[Prashantbhardwaj]

Kmittal

You're right it has been clearly reduced to two basic factors and as such there is no other solution with more surity than this possible.

[chris@veritasprep]

Here is a recent discussion on the same question: https://www.beatthegmat.com/kindly-expla ... tml#283847 Hope that helps!