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by gmatblood » Sat Nov 05, 2011 3:21 am
If n is positive, which of the following is equal to 1/((root n+1) - (root n))?

a. 1
b. root(2n+1)
c. root(n+1)/root n
d. root(n+1) - root n
e. root(n+1) + root n
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by shankar.ashwin » Sat Nov 05, 2011 3:35 am
E IMO.
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by vaibhavgupta » Sat Nov 05, 2011 3:41 am
gmatblood wrote:If n is positive, which of the following is equal to 1/((root n+1) - (root n))?

a. 1
b. root(2n+1)
c. root(n+1)/root n
d. root(n+1) - root n
e. root(n+1) + root n
Multiply root of n+1 + root n to both numerator and denominator .
denominator = 1 and nominator= root(n+1) + root n

[spoiler]Hence E it is!![/spoiler]
If OA is A, IMO B
If OA is B, IMO C
If OA is C, IMO D
If OA is D, IMO E
If OA is E, IMO A

FML!! :/
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by Anurag@Gurome » Sat Nov 05, 2011 5:26 am
gmatblood wrote:If n is positive, which of the following is equal to 1/((root n+1) - (root n))?

a. 1
b. root(2n+1)
c. root(n+1)/root n
d. root(n+1) - root n
e. root(n+1) + root n
Multiply the numerator and denominator by √(n+1) + √n, we get √(n+1) + √n/[√(n+1) - √n] * [√(n+1) + √n] = √(n+1) + √n/[n + 1 - n] = √(n+1) + √n

The correct answer is E.
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