SOLUTION: find the remainder if p(x)=2x^3-5x^2+9x-3 is divided by x-1

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Question 113773: find the remainder if p(x)=2x^3-5x^2+9x-3 is divided by x-1
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 %282x%5E3+-+5x%5E2+%2B+9x+-+3%29%2F%28x-1%29

First lets find our test zero:

x-1=0 Set the denominator x-1 equal to zero

x=1 Solve for x.

so our test zero is 1


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.
1|2-59-3
|

Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 2)
1|2-59-3
|
2

Multiply 1 by 2 and place the product (which is 2) right underneath the second coefficient (which is -5)
1|2-59-3
|2
2

Add 2 and -5 to get -3. Place the sum right underneath 2.
1|2-59-3
|2
2-3

Multiply 1 by -3 and place the product (which is -3) right underneath the third coefficient (which is 9)
1|2-59-3
|2-3
2-3

Add -3 and 9 to get 6. Place the sum right underneath -3.
1|2-59-3
|2-3
2-36

Multiply 1 by 6 and place the product (which is 6) right underneath the fourth coefficient (which is -3)
1|2-59-3
|2-36
2-36

Add 6 and -3 to get 3. Place the sum right underneath 6.
1|2-59-3
|2-36
2-363

Since the last column adds to 3, we have a remainder of 3. This means x-1 is not a factor of 2x%5E3+-+5x%5E2+%2B+9x+-+3
Now lets look at the bottom row of coefficients:

The first 3 coefficients (2,-3,6) form the quotient

2x%5E2+-+3x+%2B+6

and the last coefficient 3, is the remainder, which is placed over x-1 like this

3%2F%28x-1%29



Putting this altogether, we get:

2x%5E2+-+3x+%2B+6%2B3%2F%28x-1%29

So %282x%5E3+-+5x%5E2+%2B+9x+-+3%29%2F%28x-1%29=2x%5E2+-+3x+%2B+6%2B3%2F%28x-1%29

which looks like this in remainder form:
%282x%5E3+-+5x%5E2+%2B+9x+-+3%29%2F%28x-1%29=2x%5E2+-+3x+%2B+6 remainder 3


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