SOLUTION: Simplify: (x^4 + 10x^3 - 23x - 348x - 540) / (x + 5)

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Question 92329: Simplify: (x^4 + 10x^3 - 23x - 348x - 540) / (x + 5)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Start with the given polynomial %28x%5E4+%2B+10x%5E3+-+348x+-+540%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 10x%5E3 to -348x%5E1 there is a zero coefficient for x%5E2. This is simply because x%5E4+%2B+10x%5E3+-+348x+-+540 really looks like 1x%5E4%2B10x%5E3%2B0x%5E2%2B-348x%5E1%2B-540x%5E0
-5|1100-348-540
|

Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 1)
-5|1100-348-540
|
1

Multiply -5 by 1 and place the product (which is -5) right underneath the second coefficient (which is 10)
-5|1100-348-540
|-5
1

Add -5 and 10 to get 5. Place the sum right underneath -5.
-5|1100-348-540
|-5
15

Multiply -5 by 5 and place the product (which is -25) right underneath the third coefficient (which is 0)
-5|1100-348-540
|-5-25
15

Add -25 and 0 to get -25. Place the sum right underneath -25.
-5|1100-348-540
|-5-25
15-25

Multiply -5 by -25 and place the product (which is 125) right underneath the fourth coefficient (which is -348)
-5|1100-348-540
|-5-25125
15-25

Add 125 and -348 to get -223. Place the sum right underneath 125.
-5|1100-348-540
|-5-25125
15-25-223

Multiply -5 by -223 and place the product (which is 1115) right underneath the fifth coefficient (which is -540)
-5|1100-348-540
|-5-251251115
15-25-223

Add 1115 and -540 to get 575. Place the sum right underneath 1115.
-5|1100-348-540
|-5-251251115
15-25-223575

Since the last column adds to 575, we have a remainder of 575. This means x%2B5 is not a factor of x%5E4+%2B+10x%5E3+-+348x+-+540
Now lets look at the bottom row of coefficients:

The first 4 coefficients (1,5,-25,-223) form the quotient

x%5E3+%2B+5x%5E2+-+25x+-+223

and the last coefficient 575, is the remainder, which is placed over x%2B5 like this

575%2F%28x%2B5%29



Putting this altogether, we get:

x%5E3+%2B+5x%5E2+-+25x+-+223%2B575%2F%28x%2B5%29

So

which looks like this in remainder form:
%28x%5E4+%2B+10x%5E3+-+348x+-+540%29%2F%28x%2B5%29=x%5E3+%2B+5x%5E2+-+25x+-+223 remainder 575


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