If xy does not equal zero, what is the value of xy?
(1) 2/x + 2/y = 3
(2) x^3 - (2/y)^3 = 0
What's the best way to determine the sufficient statement?
OA B
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If xy does not equal zero, what is the value of xy
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Look at statement (1) first:lheiannie07 wrote:If xy does not equal zero, what is the value of xy?
(1) 2/x + 2/y = 3
(2) x^3 - (2/y)^3 = 0
What's the best way to determine the sufficient statement?
OA B
2/x + 2/y = 3
(2y + 2x)/xy = 3
xy = 2(x + y)/3
We don't know x + y so we can't solve for xy --> NOT SUFFICIENT!
Look at statement (2) second:
x^3 - (2/y)^3 = 0
x^3 - 8/y^3 = 0
(xy)^3 - 8 = 0
(xy)^3 = 8
xy = 2
SUFFICIENT
Where did you get stuck?
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Statement 1: 2/x + 2/y = 3lheiannie07 wrote:If xy does not equal zero, what is the value of xy?
(1) 2/x + 2/y = 3
(2) x^3 - (2/y)^3 = 0
2/x = 3 - 2/y
Case 1: y=1
Plugging y=1 into 2/x = 3 - 2/y, we get:
2/x = 3 - (2/1)
2/x = 1
2 = x
xy = 2*1 = 2.
Case 2: y=-1
Plugging y=-1 into 2/x = 3 - 2/y, we get:
2/x = 3 - (2/-1)
2/x = 5
2/5 = x
xy = (2/5)(-1) = -2/5.
Since xy can be different values, INSUFFICIENT.
Statement 2: x³ - (2/y)³ = 0
x³ = (2/y)³
x = 2/y
xy = 2.
SUFFICIENT.
The correct answer is B.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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