Hi leekaru14,
It's a good idea to TEST VALUES on a question such as this.
You mention W = 4, X = -2, but did you do the rest of the work.....
We're told that WX = Y. We're asked for the value of XY.
Fact 1: WX^2 = 16
If W = 4, X could = 2 or -2, so I'll walk you through both possibilities.
W = 4
X = 2
Y = 8
XY = 16, so the answer to the question is 16
W = 4
X = -2
Y = -8
XY = 16, so the answer to the question is 16
If W = 16, X could = 1 or -1....
W = 16
X = 1
Y = 16
XY = 16, so the answer to the question is 16
W = 16
X = -1
Y = -16
XY = 16, so the answer to the question is 16.
The answer to the question is always 16, so Fact 1 is SUFFICIENT.
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Given : wx = ythedude232 wrote:If wx=y, what is the value of xy?
(1) w(x^2) = 16
(2) y = 4
Thanks!
Question : xy = ?
Statement 1) w(x^2) = 16
i.e. (wx) * x = 16
i.e. y * x = 16
SUFFICIENT
Statement 2) y=4
Doesn't give us any clue about x therefore INSUFFICIENT
Answer: Option A
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If wx = y, what is the value of xy?
1. w(x^2) = 16
2. y = 4
Question Stem:
xy = y^2/w
St 1
w=16/x^2
So, xy = (y^2) *(x^2/16) =>xy = 16 Sufficient
St 2
y=4 Not sufficient
IMO:A
1. w(x^2) = 16
2. y = 4
Question Stem:
xy = y^2/w
St 1
w=16/x^2
So, xy = (y^2) *(x^2/16) =>xy = 16 Sufficient
St 2
y=4 Not sufficient
IMO:A
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There are two ways to solve this question, either
wx = y
multiplying x on both sides - x can be +ive or -ive will not matter since we are dealing with equality symbol.
wx * x = x * y = 16
xy = 16
answer A.
other way is to substitute values for w & x for wx^2 = 16 & get value for xy which come 16 always.
answer A.
wx = y
multiplying x on both sides - x can be +ive or -ive will not matter since we are dealing with equality symbol.
wx * x = x * y = 16
xy = 16
answer A.
other way is to substitute values for w & x for wx^2 = 16 & get value for xy which come 16 always.
answer A.
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Forget conventional ways of solving math questions. In PS, IVY approach is the easiest and quickest way to find the answer.
If wx=y, what is the value of xy?
(1) w(x^2) = 16
(2) y = 4
transforming the original condition, wx=y--> since the question asks for xy, xy=x(wx)=wx^2=?. Therefore the answer is A.
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If wx=y, what is the value of xy?
(1) w(x^2) = 16
(2) y = 4
transforming the original condition, wx=y--> since the question asks for xy, xy=x(wx)=wx^2=?. Therefore the answer is A.
www.mathrevolution.com
l The one-and-only World's First Variable Approach for DS and IVY Approach for PS that allow anyone to easily solve GMAT math questions.
l The easy-to-use solutions. Math skills are totally irrelevant. Forget conventional ways of solving math questions.
l The most effective time management for GMAT math to date allowing you to solve 37 questions with 10 minutes to spare
l Hitting a score of 45 is very easy and points and 49-51 is also doable.
l Unlimited Access to over 120 free video lessons at https://www.mathrevolution.com/gmat/lesson
Our advertising video at https://www.youtube.com/watch?v=R_Fki3_2vO8