Is the answer C?
Given, wx=y
i) wx^2=y
(wx)x=y
yx=y
INSUFFICIENT as you don'tknow the value of y.
ii) y=4 doesn't give you xy as you don't know what w is. INSUFFICIENT.
Combining both, you have xy=4.
algebra?- correction
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Source: Beat The GMAT — Data Sufficiency |
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ildude02
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Can you please explain how (i) is suficient ?
I would think from (i), we get (wx).x = y, since wx = y, we can substitute wx in the (i) equation, => y.x = y. Without knowing the value of y, I would think we don't know the value of xy. I would think answer is C as well. Even assuming we get a quadratic equationd of xy -y = 0 => y(x-1)= 0. This would mean, x can be 1 and y can take any postive value to satisfy the equation. Or, if y = 0, X can take any value. So I'm not sure how (i) is sufficient.
Appreciate anyone's input.
I would think from (i), we get (wx).x = y, since wx = y, we can substitute wx in the (i) equation, => y.x = y. Without knowing the value of y, I would think we don't know the value of xy. I would think answer is C as well. Even assuming we get a quadratic equationd of xy -y = 0 => y(x-1)= 0. This would mean, x can be 1 and y can take any postive value to satisfy the equation. Or, if y = 0, X can take any value. So I'm not sure how (i) is sufficient.
Appreciate anyone's input.
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atlantic
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In my opinion answer cannot be A. When GMAT ask for a value it asks for a specific value, not a variable. Therefore, 'y', the only thing drawn from (i) cannot be the answer. Or am I wrong?
I would go for C as well.
What is the source of this problem 'jopup'?
I would go for C as well.
What is the source of this problem 'jopup'?
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Stuart@KaplanGMAT
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Now we're making sense!jopup wrote:If wx = y, what is the value of xy?
1) wx^2=16 (<-made a correction here)
2) y=4
please explain how you got it ( if you got it)
(1) w(x^2) = 16
so:
wxx = 16
or
(wx)x = 16
sub in wx = y, we get
(y)x = 16
or
xy = 16, which is exactly what the question is asking us to solve: sufficient.
(2) y = 4
No info about x, insufficient.
(1) is sufficient alone, (2) isn't: choose (A).
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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