SOLUTION: solve using synthetic division (x^4+6x³+6x²)÷(x+5)

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Question 119007: solve using synthetic division
(x^4+6x³+6x²)÷(x+5)

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Let's simplify this expression using synthetic division


Start with the given expression %28x%5E4+%2B+6x%5E3+%2B+6x%5E2%29%2F%28x%2B5%29

First lets find our test zero:

x%2B5=0 Set the denominator x%2B5 equal to zero

x=-5 Solve for x.

so our test zero is -5


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 6x%5E2 to 0x%5E0 there is a zero coefficient for x%5E1. This is simply because x%5E4+%2B+6x%5E3+%2B+6x%5E2 really looks like 1x%5E4%2B6x%5E3%2B6x%5E2%2B0x%5E1%2B0x%5E0
-5|16600
|

Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 1)
-5|16600
|
1

Multiply -5 by 1 and place the product (which is -5) right underneath the second coefficient (which is 6)
-5|16600
|-5
1

Add -5 and 6 to get 1. Place the sum right underneath -5.
-5|16600
|-5
11

Multiply -5 by 1 and place the product (which is -5) right underneath the third coefficient (which is 6)
-5|16600
|-5-5
11

Add -5 and 6 to get 1. Place the sum right underneath -5.
-5|16600
|-5-5
111

Multiply -5 by 1 and place the product (which is -5) right underneath the fourth coefficient (which is 0)
-5|16600
|-5-5-5
111

Add -5 and 0 to get -5. Place the sum right underneath -5.
-5|16600
|-5-5-5
111-5

Multiply -5 by -5 and place the product (which is 25) right underneath the fifth coefficient (which is 0)
-5|16600
|-5-5-525
111-5

Add 25 and 0 to get 25. Place the sum right underneath 25.
-5|16600
|-5-5-525
111-525

Since the last column adds to 25, we have a remainder of 25. This means x%2B5 is not a factor of x%5E4+%2B+6x%5E3+%2B+6x%5E2
Now lets look at the bottom row of coefficients:

The first 4 coefficients (1,1,1,-5) form the quotient

x%5E3+%2B+x%5E2+%2B+x+-+5

and the last coefficient 25, is the remainder, which is placed over x%2B5 like this

25%2F%28x%2B5%29



Putting this altogether, we get:

x%5E3+%2B+x%5E2+%2B+x+-+5%2B25%2F%28x%2B5%29

So %28x%5E4+%2B+6x%5E3+%2B+6x%5E2%29%2F%28x%2B5%29=x%5E3+%2B+x%5E2+%2B+x+-+5%2B25%2F%28x%2B5%29

which looks like this in remainder form:
%28x%5E4+%2B+6x%5E3+%2B+6x%5E2%29%2F%28x%2B5%29=x%5E3+%2B+x%5E2+%2B+x+-+5 remainder 25


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