## goku3 Group Title can someone help me find the derivative to this equation 2xsqrtx^2+1 2 years ago 2 years ago

1. goku3 Group Title

$2x \sqrt{x^2+1}$

2. goku3 Group Title

actually i got all to the end of the i just can figure out how to simlify the damn thing to match the books answer

3. dpaInc Group Title

lemme do that again ... i just realized i didn't take the square root..

4. dpaInc Group Title

|dw:1333008783149:dw|

5. goku3 Group Title

4x^2/2sqrtx^2+1 +x^2+1 and i dont know how to simplify this to get 2(2x^2+1)/sqrtx^2+1

6. dpaInc Group Title

|dw:1333008899711:dw|

7. dpaInc Group Title

factor out the common factor of 2(x^2+1)^(-1/2)

8. dpaInc Group Title

|dw:1333009455298:dw|

9. goku3 Group Title

sorry i dont know what you did this is where am at 2[x(2x)/2sqrtx^2+1+sqrt x^2+1

10. CoCoTsoi Group Title

Plz see the attachment

11. CoCoTsoi Group Title

Is the photo clear? If not, I can upload another one

12. dpaInc Group Title

i can't make out what you wrote for your derivative (@ goku3)

13. goku3 Group Title

14. CoCoTsoi Group Title

15. brinethery Group Title

I agree with @CoCoTsoi 's answer.

16. brinethery Group Title

It is beauteeeful.

17. goku3 Group Title

i get lost between step to and three

18. brinethery Group Title

Chain rule

19. goku3 Group Title

why is there two 2x on top

20. brinethery Group Title

And product rule... http://tutorial.math.lamar.edu/Classes/CalcI/ProductQuotientRule.aspx

21. CoCoTsoi Group Title

one 2x is the original one. another is by diff the equation inside the sqrt

22. brinethery Group Title

So say if you have f*g. If you use the product rule, then you'll do: f'*g + f*g'.

23. brinethery Group Title

sorry if you couldn't see the tick mark next to the f.

24. goku3 Group Title

its cool how you get rid of the sqrt on top

25. brinethery Group Title

Okay so going from the 3rd to the 4th line: There's 2sqrt(x^2+1) He want's to get it so it has the same denominator as the other term. The den of the other term is sqrt(x^2+1). So with the left term, you have to multiply the numerator and denominator by sqrt(x^2+1). Then you end up with (2sqrt(x^2+1)*sqrt(x^2+1))/sqrt(x^2+1) = (2(x^2+1))/sqrt(x^2+1)

26. brinethery Group Title

lol... wants not want's. I type too fast.

27. CoCoTsoi Group Title

multiply numerator and denominator with sqrt(x^2+1)

28. goku3 Group Title

thank you guys so much every time i tried to do it i forgot to add one of the 2x and messed my entire thing up

29. brinethery Group Title

We all tend to get lost in the little steps, believe me I've been there. Coco did a great job writing that out.

30. CoCoTsoi Group Title

Coz I was lazy for typing it on keyboard so I chose to write it on paper :D

31. goku3 Group Title

paper is way faster and thank u guys for being so patient with me

32. brinethery Group Title

So goku, remember with this problem, you have to use the product rule and then the chain rule since you have stuff inside of that square root.

33. CoCoTsoi Group Title

Thanks for giving a chance for us to learn

34. goku3 Group Title

yeah i will i just have to take my on these problems and not rush them

35. brinethery Group Title

Check out paul's online notes if you haven't already, they are great :-)

36. goku3 Group Title

i have them bookmarked actually