SOLUTION: Solve the equation. 3/x+3/x-5=3x-12/x-5

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Solve the equation. 3/x+3/x-5=3x-12/x-5      Log On


   



Question 110624: Solve the equation.
3/x+3/x-5=3x-12/x-5

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
3%2Fx%2B3%2F%28x-5%29=%283x-12%29%2F%28x-5%29
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Step 1 is to look at the domain of the function. Note that either x = 0 or x = 5 results in a 0 denominator, so the domain is all real except 0 and 5.
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Step 2 is to find the common denominator. The only factors we have are x and x-5, so the only common denominator is x%28x-5%29.
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3%28x-5%29%2Fx%28x-5%29%2B3x%2Fx%28x-5%29=x%283x-12%29%2Fx%28x-5%29
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Now we need to simplify and collect like terms.
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%283x-15%2B3x%29%2Fx%28x-5%29=%283x%5E2-12x%29%2Fx%28x-5%29
%283x-15%2B3x%29=%283x%5E2-12x%29, after multiplication by x%28x-5%29
6x-15-3x%5E2%2B12x=0
3x%5E2-18x%2B15=0, after collecting terms and multiplying by -1
x%5E2-6x%2B5=0, after dividing by 3
%28x-5%29%28x-1%29=0, after factoring (given the difficulty level of this problem, I'm assuming you know how to factor a 2nd degree polynomial. If you need help with that, write me a note.
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So,
x=5 or x=1, BUT remember that 5 was excluded from the domain, therefore the only solution is x=1
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Hope this helps
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In the graph below, note the curve is asymptotic to the y-axis and there is a discontinuity at 5.
graph%28400%2C400%2C-10%2C10%2C-10%2C10%2C3%2Fx%2B3%2F%28x-5%29-%283x-12%29%2F%28x-5%29%29