Help needed - algebra-guide 2-page 89-problem 5

[SurekhaM988]

Hi,

Apologies if there is a separate thread for algebra guide book. I scanned through the threads quickly and was unable to find one. Please feel free to move this message under the correct thread.

I need help with the following question (As listed in Guide 2-Page 89- Chapter 6- Question 5 )

What is x?
1) x = 4y-4
2) xy =8

Answer is E. I am having a hard time understanding the answer. I expected it to be C as you can get x as {-8,4} and you have a quadratic equation which is not a perfect square. Please help.

[Sage Pearce-Higgins]

Please can you re-post this question under 'Manhattan Prep GMAT non-CAT Math'?

If a question in a DS problem has more than one answer, then the information is deemed to be not sufficient. For example if I ask 'How many cats does Stacey have?' and you say 'Four or five', then your information is insufficient to answer the question.