SOLUTION: use synthetic division 3x^3 - 15x^2 -42x / (x + 2)

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Question 747975: use synthetic division
3x^3 - 15x^2 -42x / (x + 2)
Answer by josgarithmetic(39623) About Me  (Show Source):
You can put this solution on YOUR website!
3x%5E3+-+15x%5E2+-42x ..........
First, factor this, and then you have a simpler dividend to use.
3x%5E3+-+15x%5E2+-42x+=+3x%2A%28x%5E2-5x-14%29

Now, you would do the division of %28x%5E2-5x-14%29%2F%28x%2B2%29, and then put back your factor of 3x.

The root being tested would be -2, so set up the synthetic div.

-2____|____1____-5____-14
______|
______|_________-2_____14
___________________________
___________1____-7_____0 Remainder is 0

This means, QUOTIENT IS 1%2Ax-7, or highlight%28x-7%29. According to the original expression to be divided, the quotient of that would be 3x%28x-7%29=highlight%283x%5E2-21%29