SOLUTION: 1-3x ______ 3x^2+14x-5 can you show me how to simplify

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Question 128546: 1-3x
______
3x^2+14x-5
can you show me how to simplify

Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
Given to simplify:
.
%281-3x%29%2F%283x%5E2%2B14x-5%29
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Since these are "setup" problems that are designed to teach a point, you can make a guess
that the numerator and the denominator have a common term that cancels out.
.
Let's re-write the numerator that it is arranged in descending powers of x ... that is
so the x term appears first followed by the constant. When we do that the problem becomes:
.
%28-3x%2B1%29%2F%283x%5E2%2B14x-5%29
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Then in the numerator, factor out -1 so that we make the 3x term positive. This makes the
expression become:
.
%28-1%29%283x-1%29%2F%283x%5E2%2B14x-5%29
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Now let's see if we can factor the denominator. And let's guess that one of the factors
might be 3x-1%29. This being the case we might begin the factoring with:
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%283x+-1%29%2A%28Ax+%2B+B%29
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We know that 3x times Ax has to equal the 3x%5E2 of the given denominator. Therefore,
A will have to equal 1 so that 3x%2A1x+=+3x%5E2. So go to our factored form of the denominator
and substitute 1 for A to make the factored form:
.
%283x-1%29%2A%281x+%2B+B%29
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Note that when we do the next step we just write the 1x as x
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Next from this factored form we can see that if we multiply the constant -1 by
B, it has to result in the -5 of the original denominator of the problem. So we can
say that:
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%28-1%29%2AB+=+-5
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and we can solve this for B by multiplying both sides by -1 to get:
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B+=+5
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Substitute this value for B in the factored form of our denominator and you have that the
factored form is:
.
%283x-1%29%2A%28x+%2B+5%29
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You can check this out by doing the multiplication just to be sure that the product is
equal to the original denominator.
.
Substitute this into the problem where we had rearranged the numerator and we now have:
.
%28-1%29%283x-1%29%2F%28%283x-1%29%2A%28x%2B5%29%29
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Cancel the common factor in the numerator with the same factor in the denominator:
.
%28-1%29%2A%28cross%283x-1%29%29%2F%28%28cross%283x-1%29%29%2A%28x%2B5%29%29
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And you are left with the simplified form:
.
-1%2F%28x%2B5%29
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and that's your answer.
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Hope this explanation helps you to understand the problem.
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