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kylexy
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Surely B....
M-N/(M+N)(M-N)=1/M+N=1/10
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kylexy
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Hunt
Surely B....
M-N/(M+N)(M-N)=1/M+N=1/10


Answer is E...i don understand either!!
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the above expr can be written as 1/(m+n) & the value of (m+n) is given by statement 2.

I will choose option B
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kylexy.. it surely can not be E... whats the source......
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Hunt
kylexy.. it surely can not be E... whats the source......
its one of the "toughies" from PR
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What is the value of (m-n)/(m*2-n*2) = ?

1.) m*2-n*2 = 40
2.) m+n = 10

I think the answer is B...But the correct answer is E..Please help me explain why????
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sahilkhurana06
What is the value of (m-n)/(m*2-n*2) = ?

1.) m*2-n*2 = 40
2.) m+n = 10

I think the answer is B...But the correct answer is E..Please help me explain why????

Moved to DS forum

I take it by m*2-n*2 you mean m^2-n^2 ?

Note that (m-n)/(m^2-n^2) = 1/(m+n) as long as m-n is not equal to 0

1) Not sufficient, as we dont know m+n
2) Would have been sufficient if we knew m-n is not 0.

1+2) Sufficient, as we know m+n and we also know m-n is not zero, as m^2-n^2=(m+n)(m-n)

So answer should be (C)
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Yes..there was some confusion..Actually the answer is C only..Thanks for giving your precious time..
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What's the final answer, B or C
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B is the answer

m^2-n^2=(m+n)(m-n) thus, (m-n)/(m+n)(m-n) equals 1/m+n

since we are given that m+n=10 we have sufficient information to answer this question with (2) alone.

B
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Bruno2000
B is the answer

m^2-n^2=(m+n)(m-n) thus, (m-n)/(m+n)(m-n) equals 1/m+n

since we are given that m+n=10 we have sufficient information to answer this question with (2) alone.

B

Nope. (check shrouded's explanation).

(M-N)/(M^2-N^2) = 1/(M+N) only possible if M =/ N or M=/ -N

1. {M^2 - N^2} = 40 => M =/ N
2. [ M + N ] = 10 => M =/ -N

Therefore, we need both. Hence, C
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I agree on B

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