## ELEEWS33 2 years ago Solve for x: x^3 -x^2 +x=8

1. Mertsj

Subtract 8 from both sides. List the possible rational roots and use synthetic division.

2. ELEEWS33

what is synthetic division?

3. Mertsj

|dw:1358823297466:dw|

4. ELEEWS33

still confused as to what that was.... please re-explain. I don't understand the image.

5. Mertsj

Perhaps you have never studied synthetic division. What class are you taking?

6. Azteck

divide that polynomial by (x-2)

7. ELEEWS33

Alg 2 and trig

8. Azteck

I will tell you why I told you to divide by x-2

9. Azteck

You have to test a number in that polynomial so that x^3-x^2+x-8=0 is true.

10. Mertsj

It won't do any good to divide by x-2 since x-2 is not a factor.

11. Azteck

if you substitute 2 for x then you get 0=0 which means 2 is a root of that polynomial.

12. Mertsj

Check your work Azteck. 2 is NOT a root

13. Azteck

Ah yes. You're right.

14. ELEEWS33

hey.. guys?! I'm still really confused as to how I'm supposed to solve this...

15. Mertsj

There is one real root of approximately 2.2 and 2 complex roots. That's from Wolfram

16. Mertsj

So perhaps you could solve it with a graphing calculator.

17. Mertsj

Are you allowed to use technology?

18. ELEEWS33

um... I still don't understand how to find x myself... without wolframalpha...

19. Mertsj

You could graph it. You could substitute values until the function changes signs and then zero in on the answer by making and checking successive guesses.

20. ELEEWS33

But I have to solve it algebraically

21. Mertsj

Sorry. I can't help you with that. Better page Satellite73

22. Mertsj

He's the brains of this outfit.

23. ELEEWS33

could you shoot him a message for me, I've not come accross him so I can't contact him.

24. Azteck

@satellite73

25. Azteck

He will get to you now.

26. Azteck

or later*

27. ELEEWS33

shoot. He doesn't accept messages from anyone he hasn't fanned :(

28. kirbykirby

This is quite difficult without software lol. Did you see the EXACT forms of the solution... one mega expression!!

29. kirbykirby

the real root, for example, is this: 1/3*(1-2 (2/(209+3 sqrt(4857)))^(1/3)+(1/2 (209+3 sqrt(4857)))^(1/3))