SOLUTION: If {{{P(x)=4x^4 - 12x^3 - 70x^2 - 9x + 8}}} find P(6) using synthetic division and the remainder theorem

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Question 138656: If P%28x%29=4x%5E4+-+12x%5E3+-+70x%5E2+-+9x+%2B+8 find P(6) using synthetic division and the remainder theorem
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
In order to evaluate P(6), simply use synthetic division

Since we want to find P(6), our test zero is 6


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.
6|4-12-70-98
|

Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 4)
6|4-12-70-98
|
4

Multiply 6 by 4 and place the product (which is 24) right underneath the second coefficient (which is -12)
6|4-12-70-98
|24
4

Add 24 and -12 to get 12. Place the sum right underneath 24.
6|4-12-70-98
|24
412

Multiply 6 by 12 and place the product (which is 72) right underneath the third coefficient (which is -70)
6|4-12-70-98
|2472
412

Add 72 and -70 to get 2. Place the sum right underneath 72.
6|4-12-70-98
|2472
4122

Multiply 6 by 2 and place the product (which is 12) right underneath the fourth coefficient (which is -9)
6|4-12-70-98
|247212
4122

Add 12 and -9 to get 3. Place the sum right underneath 12.
6|4-12-70-98
|247212
41223

Multiply 6 by 3 and place the product (which is 18) right underneath the fifth coefficient (which is 8)
6|4-12-70-98
|24721218
41223

Add 18 and 8 to get 26. Place the sum right underneath 18.
6|4-12-70-98
|24721218
4122326

Since the last column adds to 26, we have a remainder of 26. This means x-6 is not a factor of 4x%5E4+-+12x%5E3+-+70x%5E2+-+9x+%2B+8
Now lets look at the bottom row of coefficients:

The first 4 coefficients (4,12,2,3) form the quotient

4x%5E3+%2B+12x%5E2+%2B+2x+%2B+3

and the last coefficient 26, is the remainder.



According to the remainder theorem, the remainder is equal to P(6)



Answer:

So P(6)=26