GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
If x^2 + y^2 = 16 - 2xy, then (x + y)^4 =
[#permalink]
24 Mar 2018, 05:11
24 Mar 2018, 05:11
Expert Reply
00:00
Question Stats:
100% (00:53) correct
0% (00:00) wrong based on 8 sessions
Hide Show timer Statistics
If \(x^2 + y^2 = 16 - 2xy\), then \((x + y)^4 =\)
A. 4
B. 32
C. 48
D. 64
E. 256
A. 4
B. 32
C. 48
D. 64
E. 256
Sherpa Prep Representative
Joined: 15 Jan 2018
Posts: 147
Given Kudos: 0
Re: If x^2 + y^2 = 16 - 2xy, then (x + y)^4 =
[#permalink]
25 Mar 2018, 19:45
25 Mar 2018, 19:45
1
Expert Reply
Key to this one is noticing the hidden special equation. x^2 + y^2 isn't one, but it's close. If you shuffle the equation around a bit you get:
x^2 + 2xy + y^2 = 16
which can be reformatted to:
(x + y)^2 = 16
Since (x + y)^4 is (x + y)^2 squared, we can say that:
(x + y)^4 = 16^2
which is 256, giving us answer choice E.
x^2 + 2xy + y^2 = 16
which can be reformatted to:
(x + y)^2 = 16
Since (x + y)^4 is (x + y)^2 squared, we can say that:
(x + y)^4 = 16^2
which is 256, giving us answer choice E.
gmatclubot
Re: If x^2 + y^2 = 16 - 2xy, then (x + y)^4 = [#permalink]
25 Mar 2018, 19:45
Moderators:
