## anonymous 3 years ago Can anyone please help me with this question? Find Y prime: Y=cos^-1(2x+5).

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1. anonymous

This is the equation: $Y=\cos^{-1} (2x+5)$

2. anonymous

This is a new math to me and the homework is due tomorrow I m stuck with these problems!!

3. anonymous

I got an answer but it looks weird

4. anonymous

5. anonymous

what did you get? And next time, i recommend you go to the Calculus section, not the math.

6. anonymous

its $2x /\sqrt{1-4x+25}$

7. anonymous

(2x+5)=cosy

8. anonymous

-dy/dxsiny=2

9. anonymous

dy/dx=-2/siny

10. anonymous

oh so there wont be 2x anymore

11. anonymous

yup correct ur error, u'll get used to the method by practicing

12. anonymous

hmm ok

13. anonymous

it's ok to make error because from them u learn, but don't get turned off because of errors and ur close in ur answer

14. anonymous

ur not that far

15. anonymous

ok i know that numerator will be 2 but under radical is that also wrong?

16. anonymous

i m sorry i know i am asking too many stupid questions

17. anonymous

no ask any qs u like there isn't a stupid question in maths

18. anonymous

okyyy :)

19. anonymous

ok let me surprise u

20. anonymous

alright i m waiting for my surprise

21. anonymous

|dw:1360124524210:dw|

22. anonymous

can u solve the rest and tell me where did u make the mistake

23. anonymous

alright i am

24. anonymous

now ur final answer should be

25. anonymous

$\frac{ dy }{ dx }=\frac{ 1 }{ \sqrt{-x^2-5x-6} }$

26. anonymous

is the script clear because i am writing using a normal mouse

27. anonymous

yeah thats fine

28. anonymous

I m actually multiplying 2x by the power of 2 so its 4x and multipylinh 5 by the power of 2 so its giving me 25

29. anonymous

by the way give me the other 2 equations so u try and i try to solve the problem

30. anonymous

and this way we can save time

31. anonymous

oh ok

32. anonymous

but before I do that one more question just one last time can you please show me that how you got that answer on the numerator is 1 and denominator is different too.

33. anonymous

just last time then after that I ll do my other 3

34. anonymous

sure

35. anonymous

thanks

36. anonymous

|dw:1360125108009:dw|

37. anonymous

|dw:1360125325494:dw|

38. anonymous

can u see the answer now

39. anonymous

r u there?

40. anonymous

yeah sorry i was focusing deeply to that answer

41. anonymous

sorry one more question

42. anonymous

how you got 5 under that radical?

43. anonymous

44. anonymous

bcoz once you took 4 out then 10 doesnt come into table of 4

45. anonymous

sorry its 20 not 10

46. anonymous

but how we are getting 20?

47. anonymous

because (2x+5)^2= 4x^2 + 20x +25

48. anonymous

and 25-1=24

49. anonymous

4x^2+20x+24, 4(x^2+5x+6)

50. anonymous

oh GOD whats wrong with me seriously my brain really isnt working I m still stuck with this 20

51. anonymous

I m trying to figure out that how we got 20 it looks like I forgot basic math too

52. anonymous

|dw:1360126122644:dw|

53. anonymous

u haven't ur just feeling tired i know u r clever

54. anonymous

yeah no doubt I m tired I had a classes today from 8:45am to 7:05 pm

55. anonymous

thanks though

56. anonymous

what's ur major?

57. anonymous

Information Science

58. anonymous

ok good

59. anonymous

ok but once you will cancel that 2 out from denominator of 4, arent you not suppose to get 2 in denominator?

60. anonymous

not because its root4=2

61. anonymous

remember we took the 4 out of the root

62. anonymous

$1/2\sqrt{-x ^2{}}-5x-6$

63. anonymous

|dw:1360126668198:dw|

64. anonymous

yeah we did take the 4 out from the root but we are also canceling that 2 with 4 right?

65. anonymous

so u can see when we took the 16 out of the root it became 4

66. anonymous

no cancelling the 2 with root4

67. anonymous

oh ok

68. anonymous

again let me show u

69. anonymous

|dw:1360126822923:dw|

70. anonymous

alright sir I got it now thank you so much for your patience and big help :)

71. anonymous

I really appreciated

72. anonymous

ur welcome

73. anonymous

by the way how does this smart score work

74. anonymous

and kindly send me the other 3 questions

75. anonymous

oh I never worked on that smart score thing sorry

76. anonymous

oh ok I will share with you these questions

77. anonymous

$Y=\arctan(\sqrt{cscx})$

78. anonymous

hehehe wow that is a long solution but not bad, with our method we can solve almost any question

79. anonymous

$Y=\sec ^{-1}(e ^{x2})$

80. anonymous

yeah

81. anonymous

and one last question of this homework is: $Y=arc \cot(\sec 5x ^{3})$

82. anonymous

that last function e^x^2 is how ur iphone works by the way

83. anonymous

84. anonymous

lolz I dont have an iphone I carry that ordinary phones

85. anonymous

now u really have some chain rules here u have to be accurate

86. anonymous

hmm ok

87. anonymous

seriously i m giving up now I cant do this anymore ;(

88. anonymous

I m just so tired and again I have classes tomorrow frm 8:45 am and its all due tomorrow its already 12:22 am here

89. anonymous

by the way u can use the tables

90. anonymous

it would be faster

91. anonymous

ok all the best

92. anonymous

i will solve them for u

93. anonymous

hmm I feel bad though but if you can I really appreciate it

94. anonymous

its ok see u tomorrow

95. anonymous

alright thank u soo much though for your help. :) take care bye.