Events & Promotions
|
|
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.
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
25 May 2016, 10:33
Kudos
Bookmarks
If x^2 - y^2 = 12 and and x-y = 4 then x =
(a) 1.5
(b) 2.5
(c) 3.5
(d) 4.5
(e) 5.5
I tried to solve this problem in a different way than the video explanation does and unfortunately didn't come up with the same answer. Can you tell me what's wrong with my approach?
Solved 2nd equation for x: x = 4+y
I plugged this into the first equation:
(4+y)^2 -y^2 = 12 and then I solved this equation for y.
16+8y+y^2 - y^2 = 12
16+8y = 12
8 y = -4
y = -0.5 ...... and I just now realized that I made one stupid mistake with a +/- sign and that's why my answer was wrong.
Finally solved for x by: x= 4 + (-.5) which equals 3.5!
I guess this approach works too.
Right answer is C!
(a) 1.5
(b) 2.5
(c) 3.5
(d) 4.5
(e) 5.5
I tried to solve this problem in a different way than the video explanation does and unfortunately didn't come up with the same answer. Can you tell me what's wrong with my approach?
Solved 2nd equation for x: x = 4+y
I plugged this into the first equation:
(4+y)^2 -y^2 = 12 and then I solved this equation for y.
16+8y+y^2 - y^2 = 12
16+8y = 12
8 y = -4
y = -0.5 ...... and I just now realized that I made one stupid mistake with a +/- sign and that's why my answer was wrong.
Finally solved for x by: x= 4 + (-.5) which equals 3.5!
I guess this approach works too.
Right answer is C!
25 May 2016, 10:47
Kudos
Bookmarks
Silviax
Dear Silviax,
Yes, that approach does work. It's a very good thing to appreciate that many many math problems have more than one valid solution. In fact, it's often good practice, after you have solved a problem one way, to see if you can solve it in another way. The more you get comfortable with looking for alternative solutions, the more you will be able to see out-of-the-box solutions to harder problems.
Does all this make sense?
Mike
