Re: Subtracting polynomials

Hello, Urpes!

You made some errors . . .

Quote:

$\displaystyle \displaystyle \text{Simplify: }\;\frac{x+2}{(x-5)(x+2)} - \frac{2(x-7)}{(x-7)(x-5)}$

Note that:-$\displaystyle x \,\ne\, \text{-}2, 5, 7$

We have: .$\displaystyle \dfrac{x+2}{(x-5)(x+2)} - \dfrac{2(x-7)}{(x-7)(x-5)} $

Reduce: .$\displaystyle \dfrac{1}{x-5} - \frac{2}{x-5}$

Combine: .$\displaystyle \dfrac{1-2}{x-5} \;\;=\;\;\frac{-1}{x-5}$

Therefore: .$\displaystyle \dfrac{1}{5-x}$

Re: Subtracting polynomials

Ah I see, the only thing I don't get is the very last part? How did you get the denominator to be 5-x

Re: Subtracting polynomials

Soroban multiplied the top and bottom by -1 to get the last line