## nincompoop 2 years ago use the definition of derivative to find f'(x)

1. nincompoop

$f(x)=\sqrt{(x-4)}$

2. myininaya

Do you need help pluggin in or multiply by the the top's conjugate?

3. swissgirl

hmmm do you mean $\frac{f(a+h)-f(a)}{(a+h)-a}$

4. nincompoop

that is the definition of derivative @swissgirl YES :D

5. nincompoop

so you're left with $f'(x)=\frac{ \sqrt }{ h }$

6. swissgirl

$f'(x)=\frac{ \sqrt{(x+h)-4}-\sqrt{x-4}}{h}$

7. nincompoop

$f'(x)=\lim_{h \rightarrow 0}\frac{ \sqrt }{ ? }$

8. nincompoop

WTFFFFFF

9. shamil98

LOL

10. shamil98

That latex fail

11. nincompoop

why is not going through?

12. shamil98

oh gratz on 90 ss nin

13. swissgirl

Just btw my definition is not complete. This is the correct definition $\lim_{h \to 0}\frac{f(a+h)-f(a)}{(a+h)-a}$

14. nincompoop

$f'(x)=\lim_{h \rightarrow 0} \frac{ \sqrt{(x+h)-4} -(\sqrt{x-4})} { h }$

15. nincompoop

finally!!!!!!!!

16. shamil98

f(x) = (x-4)^1/2 $f'(x)= (\frac{ x-4 }{ 2 })^{\frac{ -1 }{ 2 }}$

17. nincompoop

I didn't want to pick on you, @swissgirl LAUGHING OUT LOUD but yes. without the limit would be the MVT or the mean value theorem

18. shamil98

o.o

19. nincompoop

no @shamil98 you've changed the entire thing by changing h = 2

20. nincompoop

h -> 0

21. nincompoop

you must be using a Plutonian Rule

22. swissgirl

Ok so basically the next step would be to multiply by the conjugate. Gonna write it out and scan it in cuz it will take me forever to type it in latex

23. nincompoop

I tried, omg that thing takes forever using the equation tool bar

24. nincompoop

you know at a glance, I thought it is not differentiable because it involves imaginary number and when that is the case, there's no limit with real number, hence no derivatives.

25. swissgirl

no there is a derivative just rewriting it.

26. swissgirl

27. nincompoop

i know that >.<

28. nincompoop

was showing @shamil98

29. nincompoop

how'd you scan that so quickly?

30. swissgirl

ummm it takes no longer than a half a second to scan

31. nincompoop

omg my scanner takes like a light year to scan a page

32. swissgirl

I have an issue I cant draw straight lines -_-

33. nincompoop

ruler usually solves that problem

34. swissgirl

lol thats what I usually hafta us

35. nincompoop

it is less of a technology than a scanner

36. swissgirl

hahahaha

37. nincompoop

@shamil98 yo review this LAUGHING OUT LOUD so you can skip 2 years of college in math

38. swissgirl

Ya I am great at bargaining and I managed to still get warranty coverage after the warranty was over for a year and I complained that the scanning was slow so they sent me a newer model printer which works awesome

39. nincompoop

can you send me an extra scanner then? I want the fujitsu desktop scanner. the brother machine I have is uber slow

40. swissgirl

ohhh I kept it and gave it to my bros ato destroy

41. nincompoop

bought it for 99 bucks just to have something to scan all my lab and experiment draft crap

42. swissgirl

ummm I have hp

43. swissgirl

mine was \$150 I think

44. nincompoop

yo I saw the HP one, it's "touch" technology, but it's bulky and it gets smudgie

45. swissgirl

But I gotta scan in all my work every week so it was a necessity

46. swissgirl

ya the touch aint bothersome But have not noticed it smudgy but then again I rarely print I usually scan

47. nincompoop

so do you think you can get the fujitsu desktop scanner? although it's not for high-paper scanning, it's fast and very small

48. swissgirl

for you or for me???

49. swissgirl

Not gonna waste my bargaining skills on you :P

50. nincompoop
51. nincompoop

you're mean ... just mean mean mean cheese

52. swissgirl

OMG its expensive -_-

53. swissgirl

Totally not on my budget

54. nincompoop

it's actually cheaper now. it used to be around 900

55. swissgirl

ya still dont excite me

56. nincompoop

I've been waiting for that crap to be like 200 bucks so I can buy it, but they kept discontinuing the older models

57. swissgirl

Smart guys

58. nincompoop

59. swissgirl

Did ya hear ma mayor is a crack head :D

60. nincompoop

it's fujitfrichinsu, it should be Japan

61. nincompoop

your mayor? or the re-elected Christie of NJ?

62. nincompoop

wait he's a governor LAUGHING OUT LOUD

63. swissgirl

Hey I dont live in NJ remembah

64. nincompoop

I would have bashed him for being unhealthy fat slob and use that against him he neglects his own health and that is why he doesn't care about other people's health, which is the reason why he keeps cutting the university hospital's budgets

65. swissgirl

lol ohhh I forgot u live in NJ

66. nincompoop

I am a New Yorker... LAUGHING OUT LOUD

67. swissgirl

But u do live in NJ or at least at one point u did

68. swissgirl

idk I only have one place of residence

69. nincompoop

don't you live in like NJ, NY and Canada?

70. swissgirl

I visit those places but I only live in canada. I may be coming into NJ in 2 weeks -_-

71. nincompoop

laughing out loud

72. swissgirl

Its not funny!!! idk i may just stay at home alone. Seriously dont wanna head out there