I'm looking at my notes and one of my professors steps goes from:

to

What happened to the numerator? I know this is not a mistake because when I enter the first line into my ti-89 it spits out the second line.

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- May 14th 2011, 05:36 PMCarbonHow does x/(x-1) - x/(x+1) equal 1/(x+1) + 1/(x-1) ??
I'm looking at my notes and one of my professors steps goes from:

to

What happened to the numerator? I know this is not a mistake because when I enter the first line into my ti-89 it spits out the second line. - May 14th 2011, 05:44 PMMondreus
First, notice that and that

What do you get if you put that into the given equation? - May 14th 2011, 05:51 PMCarbon
Thanks a lot. That explains it.

Although it seems like such an unusual (and unnecessary) step to take... I guess I just have to try to remember this if I see something like it again. Does this technique have a name? - May 14th 2011, 06:48 PMtopsquark
- May 14th 2011, 07:00 PMCarbon
- May 14th 2011, 07:11 PMtopsquark
- May 14th 2011, 07:12 PMMondreus

That gives me A = B = 1.