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if AB is not equal to 0, then a^-1 + b^-1 = 1) a+b 2 -(a+b)

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Intern
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if AB is not equal to 0, then a^-1 + b^-1 = 1) a+b 2 -(a+b) [#permalink] New post 18 Sep 2007, 09:04
if AB is not equal to 0, then a^-1 + b^-1 =

1) a+b
2 -(a+b)
3) 1/a+b
4) 2/a+b
5) a+b/ab

The answer is 5, but I thought it was 3...can someone explain?
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 [#permalink] New post 18 Sep 2007, 09:14
5, don't understand what you didnot understand???
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Re: GMATPrep Question [#permalink] New post 18 Sep 2007, 09:24
spf wrote:
if AB is not equal to 0, then a^-1 + b^-1 =

1) a+b
2 -(a+b)
3) 1/a+b
4) 2/a+b
5) a+b/ab

The answer is 5, but I thought it was 3...can someone explain?


simple:

a^-1 +b^-1 ---> 1/a+1/b --->make common denominators---> b/ab+a/ab = a+b/ab u don't combine the common denominators i.e. don't make it 2ab or ab +ab etc...

just ab.

ans E, er 5.
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 [#permalink] New post 18 Sep 2007, 09:32
thanks, I thought it was

a^-1 and b^-1 which is equal to 1/a + 1/b

which equals

1/a+b
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 [#permalink] New post 18 Sep 2007, 11:16
spf wrote:
thanks, I thought it was

a^-1 and b^-1 which is equal to 1/a + 1/b

which equals

1/a+b


spf
1/a + 1/b
which equals
1/a+b

--> this is blasphemy here! :)

just kidding ...if you were confused its fine...if you didnt know this then I would suggest get quant basics straight ..just a friendly advice.
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 [#permalink] New post 18 Sep 2007, 12:30
spf wrote:
thanks, I thought it was

a^-1 and b^-1 which is equal to 1/a + 1/b

which equals

1/a+b


geez.. Looks like you need to get back to your basics and refresh yourself about the fractions and their properties.

You are scaring me with that statement (1/a + 1/b) = 1/a+b)

Sorry if I come across as annoying, but I'm serious here. Were you joking when you wrote that?
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 [#permalink] New post 18 Sep 2007, 13:15
Mate you need to get your fundas clear. I am not sure if this is a joke or this is for real. How can you conclude I/a + 1/b = 1/a+b. I would recommend going through Algebra basics.
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 [#permalink] New post 18 Sep 2007, 13:20
subhen wrote:
Mate you need to get your fundas clear. I am not sure if this is a joke or this is for real. How can you conclude I/a + 1/b = 1/a+b. I would recommend going through Algebra basics.


I feel this is too harsh on the original poster. You need to understand that the OP would learn only thru such posts. Please note that all of us have our respective weaknesses. Some may be weak in math and some may be weak in verbal. So please do not discourage the original poster.

Please note that I have seen some disgusting verbal answers from people who are stars in quant. I hope you guys get the point.
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 [#permalink] New post 18 Sep 2007, 13:38
dahcrap wrote:
subhen wrote:
Mate you need to get your fundas clear. I am not sure if this is a joke or this is for real. How can you conclude I/a + 1/b = 1/a+b. I would recommend going through Algebra basics.


I feel this is too harsh on the original poster. You need to understand that the OP would learn only thru such posts. Please note that all of us have our respective weaknesses. Some may be weak in math and some may be weak in verbal. So please do not discourage the original poster.

Please note that I have seen some disgusting verbal answers from people who are stars in quant. I hope you guys get the point.


Hey spf,

I hope you have not taken suben's comment at your heart.
He might have written his comments in hurry without looking at the tone.....
You are welcome to this forum and you can throw your smallest doubts here for the clarifications.

Cheers!!
- Brajesh
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 [#permalink] New post 18 Sep 2007, 20:32
wizardofwashington wrote:
spf wrote:
thanks, I thought it was

a^-1 and b^-1 which is equal to 1/a + 1/b

which equals

1/a+b


geez..

You are scaring me with that statement (1/a + 1/b) = 1/a+b)

Sorry if I come across as annoying, but I'm serious here. Were you joking when you wrote that?


I apologize for being a bit harsh on you SPF. I tend to forget that we all started somewhere on this journey, asking the questions like yours. So, I think it was inappropriate for me to suggest you to get your basics right . I got no right to say such things.

Sorry if I came across offensively with the use of words akin to Shuben's (bot a lot subtle) and in no way my words are meant to be offensive. As "DahCrap" noted, you are welcome and please continue to share your questions, good or bad, silly or excellent, with folks around. Probably the best way to learn - by making mistakes and learning where you made the mistakes.
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 [#permalink] New post 19 Sep 2007, 05:24
Hi SPF,

My apologies as well if my comments came across to you as being rude. It was not meant to be. I guess we are all at different stages of preparation. As such the concepts that might seem easy for some of us maybe difficult for some who are just starting their prepration.

All the best for your preparation.
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Subhen

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 [#permalink] New post 19 Sep 2007, 08:55
Hey man I really reccomend that you learn your basics as everyone here has suggested.

Additionally, I reccomend that you don't spend a lot of time on the math forums. Unless you have a specific question, attempting to answer these questions at your level can be a real confindence killer. The majority of the questions posted are among the hardest, so learn ur basics and then come back and try!

Good luck.
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 [#permalink] New post 20 Sep 2007, 05:19
It was a complete oversight and obvisouly a dumb error. I did not look it over prior to the post. Thanks for the help.
  [#permalink] 20 Sep 2007, 05:19
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