View Full Version : Synthetic Division
rachelmorris
Nov 22, 2009, 10:37 PM
x to the 3rd-9x squared-8x-4/x+3=
Unknown008
Nov 23, 2009, 12:24 AM
\frac{x^3 -9x^2 - 8x-4}{x+3} = ?
Is that it?
Well here you go. I'll proceed with long division:
1. Divide x^3 by x and put the answer up there
2. Take the value you just obtained and multiply that by (x+3), putting the result below your numerator.
3. Subtract that result from your numerator.
4. Repeat with the next term.
iiiiiiiix^2 - 12x + 28
x + 3 | x^3 - 9x^2 - 8x - 4
x^3 + 3x^2
0 -12x^2 - 8x - 4
12x^2 -36x - 4
0 +28x - 4
28x + 84
0 - 88
So, your answer is x^2 + 12x + 28 with a remainder of -88.
I hope it helped! :)
mathwiz3502
Nov 29, 2009, 06:37 AM
Don't forget Unknown008 that with a remainder the answer is actually x^2+12x+28+(x+3)
(over -88)
mathwiz3502
Nov 29, 2009, 06:38 AM
(x+3)
(-88)
Unknown008
Dec 1, 2009, 04:07 AM
Actually, it's -\frac{88}{x+3} and not -\frac{x+3}{88}
Because:
x^3 - 9x^2 - 8x - 4 = (x+3)(x^2 -12x + 28) - 88
Dividing everything by (x+3) gives:
\frac{x^3 - 9x^2 - 8x - 4}{x+3} = (x^2 -12x + 28) - \frac{88}{x+3}
mathwiz3502
Dec 1, 2009, 03:31 PM
Sorry
KISS
Dec 1, 2009, 04:57 PM
Hey unky:
Why don't you teach mathwiz and us all how to write like that.
A sticky or a link.
You can show the tags using the noparse attribute.
e.g. This in bold is the Vbulletin code for This in bold
Maybe you can create a sticky someplace like "Forum Help" or the "math & Science section" Just a thought.
Unknown008
Dec 1, 2009, 10:05 PM
That's already there KISS, RickJ was the one who 'taught' me how to do so :). Check the sticky in the math-sciences page.