Limits and Derivatives

Get insights from 93 questions on Limits and Derivatives, answered by students, alumni, and experts. You may also ask and answer any question you like about Limits and Derivatives

Follow Ask Question
93

Questions

0

Discussions

4

Active Users

0

Followers

New answer posted

a month ago

0 Follower 2 Views

V
Vishal Baghel

Contributor-Level 10

x + 1 2 l o g 2 ( 3 + 2 x ) + 2 l o g 4 ( 1 0 2 x ) = 0

x + 1 + l o g 2 [ 1 0 . 2 x 1 ( 3 + 2 x ) 2 ] x = 0

( 2 x ) 2 1 4 . 2 x + 1 1 = 0

2x + y

x 1 + x 2 = l o g 2 ( 4 9 1 5 2 4 )

x 1 + x 2 = l o g 2 1 1

New answer posted

3 months ago

0 Follower 5 Views

A
alok kumar singh

Contributor-Level 10

(i) f(x)=sin x cos x

So, f?(x)=limh?0f(x+h)?f(x)h

=limh?0sin(x+h)cos(x+h)?sinxcosxh

=limh?012h*[2sin(x+h)cos(x+h)?2sinxcosx]

=limh?012h[sin2(x+h)?sin2x]

=limh?012h[2cos2(x+h)+2x2sin2(x+h)?2x2]

=limh?01h[cos(2x+h)sinh]

=limh?0cos(2x+h)*limh?0sinhh

=cos(2x+0)

=cos2x

(ii) f(x)=secx

So, f?(x)=limh?0f(x+h)?f(x)h

=limh?01h[sec(x+h)?secx]

=limh?01h[1cos(x+h)?1cosx]

=limh?01h[cosx?cos(x+h)cos(x+h)cosx]

=limh?01h[?2sin(x+x+h2)sin(x?(x+h)2)cos(x+h)cosx]

=limh?01h[?2sin(2x+h2)sin(?h/2)cos(x+h)cosx]

=limh?0(?1sin(2x+h2)cos(x+h)cosx*limh?0(?1)sinh/2h/2

=sinxcosx?cosx*1

=tanx?secx.

(iii) Given f(x)=5 sec x+4 cosx.

So, f?(x)=limh?0f(x+h)?f(x)h

=limh?05sec(x+h)+4cos(x+h)?[5secx+4cosx]h.

=limh?05h[sec(x+h)?secx]+limh?04h[cos(x+h)?cosx]

=limh?05h[1cos(x+h)?1cosx]+limh?04h[?2sin(x+h+x2)sin(x+h?x2)]

=limh?05h[cosx?cos(x+h)cos(x+h)(cosx)]+limh?04h[?2sin(2x+h2)sinh2]

=limh?05h[?2sin(2x+h2)sin(?h/2)cos(x+h)cosx]?4limh?0sin(2x+h2)limh?0sinh/2h/2

=sin(2x+02)cos(x+0)cosx*1?4sin(2x2)

=5sinxcosx?1cosx?4sinx

=5tanx?secx?4sinx

(iv) Given f(x)=cosecx

f?(x)=limh?0f(x+h)?f(x)h

=limh?01h[cosec(x+h)?cosecx]

=limh?01h[1sin(x+h)?1sinx]

=limh?01h[sinx?sin(x+h)sin(x+h)sinx]

=limh?01h[2cos(x+x+h2)sin(x?(x+h)2)]sin(x+h)sinx]

=limh?01h[2cos(x+x+h2)sin(x?(x+h)2)sin(x+h)sinx]

=limh?01h[2cos(2x+h2)sin(?h/2)]sin(x+h)sinx]

=limh?0cos(2x+h2)sin(x+h)sinx*(?1)sin(2)h/2)

=cos(2x+02)sin(x+0)sinx*(?1)

=?cosxsinx*1sinx

=?cotx?cosecx

(v) Given,f(x)=3 cot x+5cosecx.

So, f?(x)=limh?0f(x+h)?f(x)h =2cos(x+0)cosx*1+7sin(2x+02)*(?1)

=limh?03cot(x+h)+5cosec(x+h)?[3cotx+5cosx)

h?03h[cot(x+h)?cotx]+limh?0

=?5h[cosec(x+h)?cosecx]

=limh?03h[cos(x+h)sin(x+h)?cosxsinx]+limh?05h[1sin(x+h)?1sinx]

=limh?03h[cos(x+h)sinx?cosxsin(x+h)sin(x+h)sinx]+limh?05h[sinx?sin(x+h)sin(x+h)sinx]

=limh?03h[sin(x?(x+h))sin(x+h)sinx+limh?05h[2cos(x+x+h2)sin(x?(x+h)2)sin(x+h)sinx

=limh?03sin(x+h)sinx*limh?0(?1)sinhh+limh?05h[2cos(2x+h2)sin(?h/2)sin(x+h)sinx

=3sinx?sinx*(?1)+5limh

New answer posted

3 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

29.

Given, f (x) = (x-a1) (x-a2)… (x-an)

So,  limxa1f (x)=limxa1 (xa1)limxa1 (xa2)? limxa1 (xan)

= (a1-a1) (a1-a2) … (a1-an)

= 0 (a1-a2) … (a1-an)

 = 0

And limxaf (x)=limxa (xa1)limxa (xa2)limxa (xan)

= (a-a1) (a-a2) … (a-an)

New answer posted

3 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

17. Kindly go through the solution

==limx02sin2x2sin2x2

=limx0 (sinxx)2*x2limx0 (sinx2x2)2x22

= (1)2*x2*4 (1)2*x2

= 4

New answer posted

4 months ago

0 Follower 5 Views

A
alok kumar singh

Contributor-Level 10

18.  limx? 0ax+xcosxbsinx=limx? 0x (a+cosx)bsinx

=1b* (a+cos0)1

=a+1b

New answer posted

4 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

73. Given, f (x) = xsinnx

So, f?(x) = (sinxxdxdx)(xddxsinxx)(sinxx)2

= sinxxx·n(sinx)x1ddxsinx(sinx)2x

=(sinx)nx·x(sinx)n1·cosx(sinx)2n

=(sinx)n1[sinxnx·cosx](sinx)2n

=sinxn·x·cosx(sinx)2n(n1)

=sinxnxcosx(sinx)n+1

New answer posted

4 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

72. Given, f (x) = (x + sec x) (x tan x)

So, f?(x) = (x + see x) ddx(xtanx)+(xtanx)ddx(x+secx).

=(x+secx)(dxdxddxtanx)+(xtanx)(dxdx+ddxsecx)

Let g(x) = tan x.

So, g?(x) =

 

=limh01h[tan(x+h)tanx]

=limh01h[sin(x+h)cos(x+h)sinxcosx]

=limh01h[sin(x+h)cosxsinxcos(x+h)cos(x+h)cosx]

=limh01h[sin(x+hx)cos(x+h)cosx]

=limh01cos(x+h)cosx*limh0sinhh

 

=1cos2x=sec2x . _____ (2)

And P(x) = see x.

=limh0sec(x+h)secxh

=limh01h[1cos(x+h)1cosx]

=limh01h[cosxcos(x+h)cos(x+h)cosx]

=limh01h[2sin(x+x+h2)sin(x(x+h)2)cos(x+h)cosx]

 

=sinxcos2x = tan x sec x. ____ (3)

   Putting (2) and (3) in (1) we get,

   f?(x) = (x + sec x) (1 - sec2x) + (x- tan x) (1 + tan x sec x)

New answer posted

4 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

71. Given, f (x) x1+tanx

=x1+sinxcosx

=cosx·xcosx+sinx

So,f(x)=(cosx+sinx)ddx(xcosx)(xcosx)ddx(cosx+sinx)(cosx+sinx)2

 

=(cosx+sinx)(xsinx+cosx)(x·sinxcosx+xcos2x)(cosx+sinx)2

=xcosxsinx+cos2xxsin2x+sinxcosx+xsinxcosxxcos2x(cosx+sinx)2

=cos2x+sinxcosxx(sin2x+cos2x)(cosx+csinx)2

Dividing numerator and denominator by cos2x we get,

=cos2xcos2x+sinxcosx·cosxcosxx1cos2x(cosxcosx+sinxcosx)2

=1+tanxxsec2x(1+tanx)2

New answer posted

4 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

 70. Given, f (x) x2cos (π4)sinx

=x2sinx*cosπ4

So, f? (x) =

 

=cosπ4 [2·xsinxx2cosxsin2x]

=xcosπ4 [2sinxxcosxsin2x].

New answer posted

4 months ago

0 Follower 3 Views

A
alok kumar singh

Contributor-Level 10

69. Given, f (x) = 4x+5sinx3x+7cosx

So,

f(x)=(3x+7cosx)ddx(4x+5sinx)(4x+5sinx)ddx(3x+7cosx)(3x+7cosx)2

=(3x+7cosx)(4x+5cosx)(4x+5sinx)(37sinx)(3x+7cosx)2

=x+xx+x+xx+xxx+35sin2x_(3x+7cosx)2

=15xcosx+28cosx+28xsinx15sinx+35(cos2x+sin2x)(3x+7cosx)2

=35+15xcosx+28cosx+28xsinx15sinx(3x+7cosx)2

Get authentic answers from experts, students and alumni that you won't find anywhere else

Sign Up on Shiksha

On Shiksha, get access to

  • 65k Colleges
  • 1.2k Exams
  • 688k Reviews
  • 1800k Answers

Share Your College Life Experience

×

This website uses Cookies and related technologies for the site to function correctly and securely, improve & personalise your browsing experience, analyse traffic, and support our marketing efforts and serve the Core Purpose. By continuing to browse the site, you agree to Privacy Policy and Cookie Policy.