|
|
GMAT 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.
24 Sep 2020, 21:19
Kudos
Bookmarks
Alternative approach:
x^2 =y^2 can be translated as x=y and x= -y
These lines are plot as seen red and blue respectively. The question stem asks if x>0
As of now it could be in any of the four quadrants
1. Statement 1 says: 2y+1=x
This is the black line. If you observe it intersects the above two lines at 2 points x= -1 and x= 1/3. Clearly we cannot say if x>0 . Therefore 1 alone is insufficient.
2. Statement 2 says: y<=1
This line also intersects the above 2 lines at 2 points. One at x<0 and other at x>0.
Statement 2 insufficient.
Combining 1 and 2, we can see that they all intersect only at x= -1
Therefore we can say that x<0.
Attachment:
File comment: Refer
Picture1.png [ 52.7 KiB | Viewed 1379 times ]
Picture1.png [ 52.7 KiB | Viewed 1379 times ]
x^2 =y^2 can be translated as x=y and x= -y
These lines are plot as seen red and blue respectively. The question stem asks if x>0
As of now it could be in any of the four quadrants
1. Statement 1 says: 2y+1=x
This is the black line. If you observe it intersects the above two lines at 2 points x= -1 and x= 1/3. Clearly we cannot say if x>0 . Therefore 1 alone is insufficient.
2. Statement 2 says: y<=1
This line also intersects the above 2 lines at 2 points. One at x<0 and other at x>0.
Statement 2 insufficient.
Combining 1 and 2, we can see that they all intersect only at x= -1
Therefore we can say that x<0.
24 Nov 2020, 14:29
Kudos
Bookmarks
burnttwinky
\(x^2 - y^2 = 0\)
\((x+y)(x-y) = 0\)
\(x = -y\) or \(x = y\)
(1) \(x = 2y+1\)
\(y = 2y+1\)
\(y = -1 \)
or
\(-y = 2y+1\)
\(-3y = 1\)
\(y = \frac{-1}{3}\)
INSUFFICIENT.
(2) \(y ≤ -1\)
If \(x = y\), then \(x ≤ - 1\). However, if \(x = -y\), then \(x ≥ 1\). INSUFFICIENT.
(1&2)
\(2y ≤ - 2\)
\(2y + 1 ≤ -1\)
Therefore \(x ≤ -1\).
SUFFICIENT.
Answer is C.
16 Dec 2021, 02:15
Kudos
Bookmarks
burnttwinky
x^2 = y^2
or |x| = |y|
means either x=y or x=-y
1) If x=y, then x=2x+1 or x=-1
If x=-y, then x=2(-x)+1 or x=1/3
Y/N depends on whether x=y or x=-y, we don't know (Insufficient)
2) It only tells us about the sign of y, can't deduce anything about x from this (Insufficient)
c) Combined x <= 2(-1)+1, we get x <= -1; sufficient
