SOLUTION: I am still very confused on how to simplify rational expressions: This is the problem I am working on x-4 ---------- x^2-3x-4

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Question 285968: I am still very confused on how to simplify rational expressions: This is the problem I am working on
x-4
----------
x^2-3x-4

Found 2 solutions by richwmiller, josmiceli:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
The best way to write this for us is
(x-4)/(x^2-3x-4)
This way clarifies for us exactly what is the numerator and what is the denominator
To make it look nice surround it by 3 { and 3}
%28x-4%29%2F%28x%5E2-3x-4%29
My guess just looking at it would be that x-4 might be a factor of (x^2-3x-4)
so we are looking for factors of -4 which add up to -3,
-4 and 1 work
(x-4)*(x+1)= (x^2-3x-4)
(x-4)/(x^2-3x-4) =
(x-4)/x-4)*(x+1)=
1/x+1

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I think you're confused about what
is a factor and what's not.
Suppose you had this fraction:
%286%2A6%2A6%2A11%2A11%2A11%2A11%29%2F%28377%2A11%2A11%2A11%2A11%29
The 4 11's on top- cancel the 4 11's
on the bottom.
Now suppose you had

You've still got 7 factors on top and 5 factors on the bottom
Each of the x-11's is a factor and the 4 on the bottom cancel the 4 on the top.
Your problem is:
%28x-4%29%2F%28x%5E2+-+3x+-+4%29
The bottom factors to
%28x+-+4%29%2A%28x+%2B1%29 so, you have
%28x-4%29%2F%28%28x-4%29%2A%28x%2B1%29%29+=+1%2F%28x%2B1%29
If your problem is factoring the denominator, you just
have to keep backtracking until you clear up all confusions