SOLUTION: Divide 5x^3 - 5x + 1 by x -3 Do i have the right answer 5x^2-15x-40

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Question 76465: Divide 5x^3 - 5x + 1 by x -3
Do i have the right answer 5x^2-15x-40

Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
Check to make sure that you copied the problem correctly. If the problem is correct as
you posted it, the answer is 5x%5E2+%2B+15x+%2B+40+%2B%28121%2F%28x-3%29%29
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If you posted the problem correctly, then I suspect that you are adding not subtracting
during the division process.
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For example. You got the first division correct ... and the first quotient term is, as you
found, 5x%5E2. When you multiply this back times the divisor x-3 the product is:
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5x%5E3+-+15x%5E2
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when you subtract this from 5x%5E3+%2B+0x%5E2 you CHANGE THE SIGNS of 5x%5E3+-+15x%5E2 to
get -5x%5E3+%2B+15x%5E2+ and then you add this to 5x%5E3+%2B+0x%5E2. The result is:
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%2B15x%5E2.
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You then bring down the -5x term. So the next division is x-3 into 15x%5E2+-+5x.
This division will result in +15x and multiplying it back the %2B15x times x-3
results in 15x%5E2+-+45x. Subtract this from 15x%5E2+-+5x. Do that by changing the
signs to -15x%5E2+%2B45x and adding it to 15x%5E2+-+5x to get %2B40x.
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Divide the 40x by x-3 to get 40. Back multiply this to get 40%2A%28x-3%29
equals 40x+-+120. Subtract this from 40x+%2B+1 by changing the signs to
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-40x+%2B+120 and adding that to 40x%2B1 to get 121. The 121 is the remainder
and it can be divided by the divisor %28x-3%29. This will make the answer to this division
problem:
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. 5x%5E2+%2B+15x+%2B+40 with a remainder of 121%2F%28x-3%29
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Hope this helps you to understand the process of algebraic long division.
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