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xy

by sogmat » Sat Dec 27, 2008 9:37 pm
Q23:
If x = 0 and x = sq rt(8xy-16y^2) , then, in terms of y, x =
A. – 4y
B. y/4
C. y
D. 4y
E. 4y^2

OA D[spoiler][/spoiler]
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by mental » Sat Dec 27, 2008 11:06 pm
x = sq rt (8xy -16y^2)

square both sides
x^2 = 8xy - 16y^2
x^2 - 8xy + 16y^2 = 0

(x - 4y)^2 = 0
x = 4y

Ans: D
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Re: xy

by aroon7 » Sun Dec 28, 2008 10:12 am
sogmat wrote:Q23:
If x = 0 and x = sq rt(8xy-16y^2) , then, in terms of y, x =
A. – 4y
B. y/4
C. y
D. 4y
E. 4y^2

OA D[spoiler][/spoiler]
Is it "If x = 0..." or "If x not = 0...?"
if x = 0 then y is also 0. then all answer choices are right.
am i wrong somewhere?

Thanks!
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