Math Is Fun Forum

4littlepiggiesmom

Member

Registered: 2006-01-09

Posts: 42

rational expressions and functions

first problem:
1 /(a-b)  - 3/(a+b)
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2/(b-a)  +  4/(b+a)       

I've been working on it for over week and can't get the answer of (2b-a)/(a-3b) to work out?

second probelm:

(1-8x^-3)/(x^-1 +2x^-2 +4x^-3)  again a=have tried a million times and nothing loooks like the answer of x-2?

Please help I'm a back to college student after taking a 20 year break and can't remeber this stuff from before! Thanks to any and all. Heidi

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: rational expressions and functions

The first one isn't too bad, it's just lots of work.

Hopefully that's clear enough.

For the second one, you use polynomial division. It might help to multiply every term by x³ first, to get rid of the negative powers.

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Why did the vector cross the road?
It wanted to be normal.