Which of the following is true?

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Which of the following is true?

by patelv » Mon Sep 13, 2010 2:16 am
If a,b and c are positive numbers with no common factors and such that 1/a + 1/b = 1/c then which of the following is true?

a) (a+b) is a square.
b) (b+c) is a square.
c) (c+a+b) is a square.
d) None of these.
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by sanju09 » Mon Sep 13, 2010 3:22 am
patelv wrote:If a,b and c are positive numbers with no common factors and such that 1/a + 1/b = 1/c then which of the following is true?

a) (a+b) is a square.
b) (b+c) is a square.
c) (c+a+b) is a square.
d) None of these.

Theme doesn't portray GMAT.

If 1/a + 1/b = 1/c, then a + b = a b/c, how do we know it's a square? Leave (A). Furthermore, b + c and c + a + b cannot be obtained from 1/a + 1/b = 1/c, hence leave (B) and (C) too. Take home [spoiler]D

Eerie query
[/spoiler]
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