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New answer posted

a year ago

0 Follower 22 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  f(x)=cos(x2+1)                                                             …(i)⇒  f(x+Δx)=cos[(x+Δx)2+1]                                      …(ii)Subtracting  eqn.(i)  from  eqn.(ii)             f(x+Δx)−f(x)=cos[(x+Δx)2+1]−cos(x2+1)Dividing  both  sides  by  Δx  we  get             f(x+Δx)−f(x)Δx=cos[(x+Δx)2+1]−cos(x2+1)Δx             limΔx→0f(x+Δx)−f(x)Δx=limΔx→0cos[(x+Δx)2+1]−cos(x2+1)Δx      f'(x)=limΔx→0cos[(x+Δx)2+1]−cos(x2+1)Δx                    =limΔx→0−2sin[(x+Δx)2+1+x2+12].sin[(x+Δx)2+1−x2−12]Δx                   =limΔx→0−2sin[x2+Δx2+2xΔx+x2+22].sin[x2+Δx2+2xΔx−x22]Δx                   =limΔx→0−2sin[x2+Δx22+xΔx+1].sin[Δx(Δx+2x)2]Δx                   =limΔx→0−2sin[x2+Δx22+xΔx+1].sin[Δx(Δx+2x)2]Δx[Δx+2x2]*[Δx+2x2]                   =limΔx[Δx+2x2]→0−2sin[x2+Δx22+xΔx+1]sin[Δx(Δx+2x)2]Δx[Δx+2x2]*[Δx+2x2]Taking limit ,  we  have                    =−2sin(x2+1).1.(x)=−2xsin(x2+1).

New answer posted

a year ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y= 1ax2+bx+c      dydx=ddx(1ax2+bx+c)             =(ax2+bx+c)ddx(1)−1.ddx(ax2+bx+c)(ax2+bx+c)2                    [  Using quotient  rule]             =(ax2+bx+c)*0−(2ax+b)(ax2+bx+c)2=−(2ax+b)(ax2+bx+c)2

New answer posted

a year ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=sin3xcos3x      dydx=ddx(sin3xcos3x)             =sin3xddx(cos3x)+cos3x.ddx(sin3x)                    [Using  product  rule]             =sin3x.3cos2x(−sinx)+cos3x.3sin2x.cosx             =−3sin4x.cos2x+3cos4x.sin2x             =3sin2x.cos2x(−sin2x+cos2x)=3sin2x.cos2x.cos2x             =34.4sin2x.cos2x.cos2x=34(2sinx.cosx)2.cos2x             =34sin22x.cos2x

New answer posted

a year ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=x2sinx+cos2x      dydx=ddx (x2sinx+cos2x)             =ddx (x2sinx)+ddx (cos2x)             =x2cosx+sinx.2x+ (−2sin2x)             =x2cosx+2xsinx−2sin2x

New answer posted

a year ago

0 Follower 3 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=(2x−7)2(3x+5)3      dydx=ddx(2x−7)2(3x+5)3             =(2x−7)2ddx(3x+5)3+(3x+5)3ddx(2x−7)2                    [Using  product  rule]             =(2x−7)2.3(3x+5)2.3+(3x+5)3.2(2x−7).2             =9(2x−7)2(3x+5)2+4(3x+5)3(2x−7)             =(2x−7)(3x+5)2[9(2x−7)+4(3x+5)]             =(2x−7)(3x+5)2[18x−63+12x+20]             =(2x−7)(3x+5)2(30x−43)=(2x−7)(30x−43)(3x+5)2

New answer posted

a year ago

0 Follower 4 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=(sinx+cosx)2      dydx=ddx(sinx+cosx)2             =2(sinx+cosx)ddx(sinx+cosx)             =2(sinx+cosx)(cosx−sinx)             =2(cos2x−sin2x)=2cos2x              [?cos2x=cos2x−sin2x]

New answer posted

a year ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=a+b sinxc+dcosx      dydx=ddx(a+b sinxc+dcosx)             =(c+dcosx)ddx(a+b sinx)−(a+b sinx)ddx(c+dcosx)(c+dcosx)2                     [  Using quotient  rule]             =(c+dcosx)(b cosx)−(a+b sinx)ddx(−dsinx)(c+dcosx)2             =cbcosx+bdcos2x+adsinx+bdsin2x(c+dcosx)2             =cbcosx+adsinx+bd(sin2x+cos2x)(c+dcosx)2             =cbcosx+adsinx+bd(c+dcosx)2

New answer posted

a year ago

0 Follower 3 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=(ax2+cotx)(p+q cosx)      dydx=ddx(ax2+cotx)(p+q cosx)             =(ax2+cotx)ddx(p+q cosx)+(p+q cosx)ddx(ax2+cotx)                     [Using  product  rule]             =(ax2+cotx)(−qsinx)+(p+q cosx)(2ax−cosec2x)             =−qsinx(ax2+cotx)+(p+q cosx)(2ax−cosec2x)

New answer posted

a year ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=x2cosπ4sinx      dydx=ddx(x2cosπ4sinx)             =cosπ4.ddx(x2sinx)             =12[sinxddx(x2)−x2ddx(sinx)]sin2x            [  quotient  rule]             =12.[sinx.2x−x2cosxsin2x]=12[2xsinx−x2cosxsin2x]              =12[2xcosecx−x2cotxcosecx]=x2cosecx[2−xcotx]

New answer posted

a year ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

This is a Short Answer Type Questions as classified in NCERT Exemplar

Sol:

Let  y=x5−cosxsinx      dydx=ddx(x5−cosxsinx)             =sinxddx(x5−cosx)−(x5−cosx)ddx(sinx)sin2x            [  quotient  rule]             =sinx(5x4+sinx)−(x5−cosx)(cosx)sin2x              =5x4.sinx+sin2x−x5cosx+cos2xsin2x              =5x4.sinx−x5cosx+(sin2x+cos2x)sin2x=5x4.sinx−x5cosx+1sin2x

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