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.
(–x + y)(–y + x) = x2 – y2 y2 – x2 0 –(x – y)2 (y – x)2
[#permalink]
15 Apr 2018, 03:49
15 Apr 2018, 03:49
Expert Reply
00:00
Question Stats:
90% (00:42) correct
9% (01:39) wrong based on 11 sessions
Hide Show timer Statistics
\((-x + y)(-y + x) =\)
A. \(x2 - y2\)
B. \(y^2 - x^2\)
C. 0
D. \(-(x - y)^2\)
E. \((y - x)^2\)
A. \(x2 - y2\)
B. \(y^2 - x^2\)
C. 0
D. \(-(x - y)^2\)
E. \((y - x)^2\)
Drill 2
Question: 7
Page: 511
Question: 7
Page: 511
Re: (–x + y)(–y + x) = x2 – y2 y2 – x2 0 –(x – y)2 (y – x)2
[#permalink]
16 Apr 2018, 02:29
16 Apr 2018, 02:29
1
expand the expression
\((-x + y)(-y + x) = xy -x^2 -y^2 + xy\)
or, \((-x + y)(-y + x) = 2xy -x^2 - y^2\)
or, \((-x + y)(-y + x) = -(-2xy + x^2 + y^2)\)
The expression inside the bracket is similar to \((a-b)^2\) so in that format
The expression reduces to \(-(x - y)^2\)
option D
\((-x + y)(-y + x) = xy -x^2 -y^2 + xy\)
or, \((-x + y)(-y + x) = 2xy -x^2 - y^2\)
or, \((-x + y)(-y + x) = -(-2xy + x^2 + y^2)\)
The expression inside the bracket is similar to \((a-b)^2\) so in that format
The expression reduces to \(-(x - y)^2\)
option D
Re: (–x + y)(–y + x) = x2 – y2 y2 – x2 0 –(x – y)2 (y – x)2
[#permalink]
22 Apr 2018, 12:16
22 Apr 2018, 12:16
Expert Reply
Explanation
Factor out \(-1\) from the parentheses on the left and rearrange the expression in the parentheses on the right to get \(-1(x - y) (x - y) = -(x - y)^2\). The answer is choice (D).
Factor out \(-1\) from the parentheses on the left and rearrange the expression in the parentheses on the right to get \(-1(x - y) (x - y) = -(x - y)^2\). The answer is choice (D).
