SOLUTION: I need help solving this complex fraction please? 5/(2x^2-18) - 2/(x^2-7x+12) all over 2/(x^2-x-12) - 4/(3x^2-27) Thank you

Algebra ->  Equations -> SOLUTION: I need help solving this complex fraction please? 5/(2x^2-18) - 2/(x^2-7x+12) all over 2/(x^2-x-12) - 4/(3x^2-27) Thank you      Log On


   



Question 882289: I need help solving this complex fraction please?
5/(2x^2-18) - 2/(x^2-7x+12) all over 2/(x^2-x-12) - 4/(3x^2-27)
Thank you

Found 2 solutions by DrBeeee, Edwin McCravy:
Answer by DrBeeee(684) About Me  (Show Source):
You can put this solution on YOUR website!
I'm very slow at typing etc so I wont show all the steps.
The most important step is to FACTOR ALL FOUR denominators of the given expression;
(1) 2x^2 - 18 = 2*(x-3)*(x+3)
(2) x^2 -7x +12 = (x-3)*(x-4)
(3) x^2-x-12 = (x-4)*(x+3)
(4) 3x^2-27 = 3*(x-3)*(x+3)
Then factor out a common factor of the numerator
(5) 1/(x-3) and from the denominator
(6) 2/(x+3)
Add the two similar fraction in the numerator to get
(7) (x-32)/(2*(x+3)*(x-4)), and add the denominator fractions to get
(8) (x-1)/(3*(x-4)*(x-3))
At this point you have a few common factors that cancel, namely,
(9) (x-3),(x+3) and (x-4) leaving your answer
(10) 3/4*((x-32)/(x-1))
Note that you should include any values of x that render the expression undedined (divide by zero), they are x not equal to {1,-3,+3,4}

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Here is a way that shows even more detail:



As the good doctor above says, factor all the four denominators

Factor: 2x%5E2-18=2%28x%5E2-9%29=2%28x-3%29%28x%2B3%29
Factor: x%5E2-7x%2B12=%28x-3%29%28x-4%29
Factor: x%5E2-x-12=%28x%2B3%29%28x-4%29
Factor: 3x%5E2-27=3%28x%5E2-9%29=3%28x-3%29%28x%2B3%29



The LCD of all those denominators is red%286%28x-3%29%28x%2B3%29%28x-4%29%29

Put it over 1: expr%28red%28%286%28x-3%29%28x%2B3%29%28x-4%29%29%2F1%29%29

and multiply every term in the numerator and denominator by it:



Then you cancel as much as you can:



%2815%28x-4%29-12%28x%2B3%29%29%2F%2812%28x-3%29-8%28x-4%29%29

%2815x-60-12x-36%29%2F%2812x-36-8x%2B32%29

%283x-96%29%2F%284x-4%29

You can leave it like that or else you can factor out a common
factor in the numerator and denominator:

%283%28x-32%29%29%2F%284%28x-1%29%29

Edwin