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## Homework Statement

y = [tex]\frac{1}{(x-1)(x+2)}[/tex]

find out the domain and range

ans: y<= -4/9 or y>0

[tex]x~E~R~-\{-2,1\}[/tex]

## The Attempt at a Solution

I know the solution and I used this methoD:

y(x^2 + x -2) =1 (where [tex]y\neq0[/tex] )

when x is real, the discriminant

y^2 -4y(-2y-1) >=0 (where [tex]y\neq0[/tex] )

9y^2 + 4y >= 0 (where [tex]y\neq0[/tex] )

y(9y +4) >= 0 (where [tex]y\neq0[/tex] )

y<= -4/9 or y>0

__My request is ... plz use some other easy method to illustrate this problem.. I want to know other methods of solving this same problem.. plz help.__====================================================================

Forum $ignature: www.lingouist.blogspot.com[/URL]

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