SOLUTION: What is the remainder when 4x3 + 5x2 - 13x - 7 is divided by x - 2? I came up with -33 is this correct?

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Question 90279: What is the remainder when 4x3 + 5x2 - 13x - 7 is divided by x - 2?

I came up with -33 is this correct?

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Start with the given polynomial %284x%5E3+%2B+5x%5E2+-+13x+-+7%29%2F%28x-2%29

First lets find our test zero:

x-2=0 Set the denominator x-2 equal to zero
x=2 Solve for x.

so our test zero is 2


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.
2|45-13-7
|

Start by bringing down the leading coefficient (it is the coefficient with the highest exponent which is 4)
2|45-13-7
|
4

Multiply 2 by 4 and place the product (which is 8) right underneath the second coefficient (which is 5)
2|45-13-7
|8
4

Add 8 and 5 to get 13. Place the sum right underneath 8.
2|45-13-7
|8
413

Multiply 2 by 13 and place the product (which is 26) right underneath the third coefficient (which is -13)
2|45-13-7
|826
413

Add 26 and -13 to get 13. Place the sum right underneath 26.
2|45-13-7
|826
41313

Multiply 2 by 13 and place the product (which is 26) right underneath the fourth coefficient (which is -7)
2|45-13-7
|82626
41313

Add 26 and -7 to get 19. Place the sum right underneath 26.
2|45-13-7
|82626
4131319

Since the last column adds to 19, we have a remainder of 19. This means x-2 is not a factor of 4x%5E3+%2B+5x%5E2+-+13x+-+7
Now lets look at the bottom row of coefficients:

The first 3 coefficients (4,13,13) form the quotient

4x%5E2+%2B+13x+%2B+13

and the last coefficient 19, is the remainder.

So the remainder is 19

note: it looks like you added -26 and -7 to get -33. Instead you should add 26 and -7 to get 19





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