Christos 3 years ago Can you teach me how to do long division?

1. Luigi0210

Any specific examples..?

2. anonymous

I can teach you my more kid-friendly approach to long division, if that's okay with you.

3. Christos

2x^3-3x^2-36x+5

4. anonymous

Oh that sort of long division... Yeah I always forget that. Luigi, I summon thee!

5. Luigi0210

What are you dividing it by?

6. Christos

diving by x - 5

7. Luigi0210

There's an easier way. Have you learned synthetic division?

8. Christos

No can you teach me please

9. Luigi0210

Synthetic division is like upside down division. So for the problem $\frac{ 2x^3-3x^2-36x+5 }{ x-5 }$ It would look like this: |dw:1368504397441:dw|

10. Christos

the result is 2x^3+7x-1 ?

11. Luigi0210

no 2x^2

12. Christos

can you explain to me how you got those numbers at your image

13. Christos

These ones http://screencast.com/t/lqjFKcJA

14. Luigi0210

For synthetic division first what you do is solve for x: x-5=0 x=5 -------------------------------------------------- Now just take the coefficients of the equation and plug them in. When it is set up you then drop the first number, like in the example we dropped the 2. Next we would multiply it by 5 and add it to the next coefficient and then repeat. So 5*2 is 10. and -3+10 is 7.and 7*5 is 35. 35+-36 which is -1. and -1*5 is -5 and so on

15. Christos

thank you

16. Luigi0210

Synthetic division only works with linear equations.

17. Christos

what do you mean by "linear" ?

18. Christos

@Luigi0210

19. Luigi0210

Like you can't use this method if you're dividing by like x^2 and beyond. It only works with x+5, x-2, 5x+9, etc.

20. Christos

I see :)