## anonymous 5 years ago logarithms anyone?

1. bahrom7893

i gotta revise those too, so what are the questions?

2. anonymous

how do i get the inverse y=logsub3x

3. anonymous

so its y=(little3at the bottom)x

4. bahrom7893

k

5. bahrom7893

$y=\log_{3}x$ $3^{y}=x$ So x = y^3 is that what u mean by inverse?

6. anonymous

the inverse of the function

7. anonymous

i dont get that either

8. bahrom7893

http://www.andrews.edu/~calkins/math/webtexts/numb17.htm sorry havent done logs in a long time, i only use Ln,s but that is the inverse function

9. bahrom7893

inverse function is: Say: y = f(x) then inverse is: x = F^-1 (y), which basically means solve for X

10. anonymous

ok thank you soo much

11. bahrom7893

hey can u check the answer key.. like gimme any problem with an answer to it

12. bahrom7893

and ill make sure the answer's right

13. anonymous

answer key? like in the back of the book?

14. anonymous

ummm, this is a unit 4 test that was left for hw, so we cant look at the answers in the back of the book T_T

15. bahrom7893

just gimme any similar problems from the book that has an answer to it

16. bahrom7893

like anything like y = log(sub5)x and then it has an answer.. numbers dont matter

17. anonymous

ok, wait a sec

18. anonymous

13. y=logsubX

19. anonymous

20. anonymous

21. bahrom7893

u forgot to add what is under sub

22. anonymous

sorry the second is the real answer

23. anonymous

there is no under sub

24. bahrom7893

Oh its just $y = \log_{} x$

25. bahrom7893

?

26. anonymous

ya, its: y=log(undersub7) X

27. anonymous

28. bahrom7893

Okay that makes sense now

29. anonymous

sorry if i confused you!

30. bahrom7893

So my answer wasn't technically wrong but still it was in wrong notation

31. bahrom7893

workin on the first one

32. anonymous

oh alright

33. bahrom7893

$y=\log_{3}x ; x = 3^{y} ; f ^{-1} (x) = 3^{x}$

34. anonymous

i understood everything till the last setp

35. bahrom7893

oh for you to make it into inverse, just replace y with x, say: Sin(x) = y; Sin^-1(y) = x

36. anonymous

so would i have to put it as : $\prime-1(x)=3^{x}$

37. anonymous

i meant f^-1(x)=3^x

38. bahrom7893

yes

39. anonymous

hmm, i was pretty sure you could have answered it differently. it cant be: y=3^x

40. bahrom7893
41. anonymous

oh thanks that seems helpful, can i ask 1 more and see if i get it?

42. bahrom7893

yeah

43. anonymous

f(x)=lnx

44. anonymous

ok, i dont even know what to do here,

45. anonymous

we basically solve for x, right?

46. bahrom7893

yup and this is my favourite stuff! so useful in calculus

47. bahrom7893

k so Lnx is the same as Log(sub e)X, where e is approximately 2.71

48. anonymous

right

49. anonymous

oh,. sorry, how can i add you as a fan?

50. anonymous

oh, nvm, haha

51. bahrom7893

sure lol

52. anonymous

ok, so i get it so far

53. bahrom7893

good and start a new topic. this is getting annoying, my browser keeps scrollin up and down. this place is buggy

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