SOLUTION: Divide X^4+X^2-80 over x+3

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Question 90640: Divide
X^4+X^2-80
over
x+3
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

Start with the given polynomial

First lets find our test zero:

Set the denominator equal to zero
Solve for x.

so our test zero is -3


Now set up the synthetic division table by placing the test zero in the upper left corner and placing the coefficients of the numerator to the right of the test zero.(note: remember if a polynomial goes from to there is a zero coefficient for . This is simply because really looks like
-3|1010-80
|

Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 1)
-3|1010-80
|
1

Multiply -3 by 1 and place the product (which is -3) right underneath the second coefficient (which is 0)
-3|1010-80
|-3
1

Add -3 and 0 to get -3. Place the sum right underneath -3.
-3|1010-80
|-3
1-3

Multiply -3 by -3 and place the product (which is 9) right underneath the third coefficient (which is 1)
-3|1010-80
|-39
1-3

Add 9 and 1 to get 10. Place the sum right underneath 9.
-3|1010-80
|-39
1-310

Multiply -3 by 10 and place the product (which is -30) right underneath the fourth coefficient (which is 0)
-3|1010-80
|-39-30
1-310

Add -30 and 0 to get -30. Place the sum right underneath -30.
-3|1010-80
|-39-30
1-310-30

Multiply -3 by -30 and place the product (which is 90) right underneath the fifth coefficient (which is -80)
-3|1010-80
|-39-3090
1-310-30

Add 90 and -80 to get 10. Place the sum right underneath 90.
-3|1010-80
|-39-3090
1-310-3010

Since the last column adds to 10, we have a remainder of 10. This means is not a factor of
Now lets look at the bottom row of coefficients:

The first 4 coefficients (1,-3,10,-30) form the quotient



and the last coefficient 10, is the remainder, which is placed over like this





Putting this altogether, we get:



So

which looks like this in remainder form:
remainder 10


You can use this online polynomial division calculator to check your work
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