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Class 12-commerce RD SHARMA Solutions Maths Chapter 15: Mean Value Theorems

Mean Value Theorems Exercise Ex. 15.1

Solution 1(i)

Solution 1(ii)

Solution 1(iii)

Solution 1(iv)

Solution 1(v)

Solution 1(vi)

Solution 2(i)

Solution 2(iii)

Solution 2(iv)

Solution 2(v)

Solution 2(vi)

Solution 2(vii)

Solution 2(viii)

Solution 3(i)

Solution 3(ii)

Solution 3(iii)

Solution 3(iv)

Solution 3(v)

Solution 3(vi)

Solution 3(vii)

Here,

            f open parentheses x close parentheses equals fraction numerator sin x over denominator e to the power of x end fraction space o n space x space element of open square brackets 0 comma space straight pi close square brackets
W e space k n o w space t h a t comma space e x p o n e n t i a l space a n d space sin e space b o t h space f u n c t i o n s space a r e space c o n t i n u o u s space a n d space d i f f e r e n t i a b l e
e v e r y space w h e r e comma space s o space f open parentheses x close parentheses space i s space c o n t i n u o u s space i s space open square brackets 0 comma space straight pi close square brackets space a n d space d i f f e r e n t i a b l e space i s space open square brackets 0 comma space straight pi close square brackets

Now comma space

space space space space space space space space space space space space space straight f open parentheses 0 close parentheses equals fraction numerator sin space 0 over denominator straight e to the power of 0 end fraction equals 0
space space space space space space space space space space space space space space
space space space space space space space space space space space space space space space straight f open parentheses straight pi close parentheses equals fraction numerator sin space straight pi over denominator straight e to the power of straight pi end fraction equals 0

rightwards double arrow straight f open parentheses 0 close parentheses equals straight f open parentheses straight pi close parentheses
Since space Rolle apostrophe straight s space theorem space applicable comma space therefore space there space must space exist space straight a space point space straight c element of open square brackets 0 comma space straight pi close square brackets
such space that space straight f apostrophe open parentheses straight c close parentheses equals 0

Now comma
space space space space space space space space space space straight f open parentheses straight x close parentheses equals sinx over straight e to the power of straight x

space space space space space space space space space space rightwards double arrow straight f apostrophe open parentheses straight x close parentheses equals fraction numerator straight e to the power of straight x open parentheses cosx close parentheses minus straight e to the power of straight x open parentheses sinx close parentheses over denominator open parentheses straight e to the power of straight x close parentheses squared end fraction
Now comma
space space space space space space space space space space space space space space space space straight f apostrophe open parentheses straight c close parentheses equals 0
space space space space space space space space space space space rightwards double arrow straight e to the power of straight c open parentheses cosc minus sinc close parentheses equals 0
space space space space space space space space space space space rightwards double arrow space straight e to the power of straight c not equal to 0 space and space cosc minus sinc equals 0
space space space space space space space space space space space rightwards double arrow space tanc equals 1
space space space space space space space space space space space space space space space straight c equals straight pi over 4 element of open square brackets 0 comma straight pi close square brackets
Hence comma space Rolle apostrophe straight s space theorem space is space verified.

Solution 3(viii)

Solution 3(ix)

Solution 3(x)

Solution 3(xi)

Solution 3(xii)

Solution 3(xiii)

Solution 3(xiv)

Solution 3(xv)

Solution 3(xvi)

Solution 3(xvii)

Solution 3(xviii)

Solution 7

x = 0 then y = 16

Therefore, the point on the curve is (0, 16) 

Solution 8(i)

x = 0, then y = 0

Therefore, the point is (0, 0)

Solution 8(ii)

Solution 8(iii)

x = 1/2, then y = - 27

Therefore, the point is (1/2, - 27)

Solution 9

Solution 10

Solution 11

Solution 2(ii)

Given function is

As the given function is a polynomial, so it is continuous and differentiable everywhere.

Let's find the extreme values

  

  

Therefore, f(2) = f(6).

So, Rolle's theorem is applicable for f on [2, 6].

Let's find the derivative of f(x)

  

Take f'(x) = 0

  

As 4 [2, 6] and f'(4) = 0.

Thus, Rolle's theorem is verified.

Mean Value Theorems Exercise Ex. 15.2

Solution 1(i)

Solution 1(ii)

Solution 1(iii)

Solution 1(iv)

Solution 1(v)

Solution 1(vi)


Solution 1(vii)

Solution 1(viii)

Solution 1(ix)

Solution 1(x)

Solution 1(xi)

Solution 1(xii)


Solution 1(xiii)

Solution 1(xiv)

Solution 1(xv)

Solution 1(xvi)


Solution 2

Solution 3

Solution 4

Solution 5

Solution 6


Solution 7

Solution 8

Solution 9

Solution 10

Solution 11

Mean Value Theorems Exercise MCQ

Solution 1

Correct option: (c)

 

  

Solution 2

Correct option: (c)

 

  

Solution 3

Correct option: (b)

Solution 4

Correct option: (c)

 

Using statement of Lagrange's mean value theorem function is continuous on [a,b], differentiable on (a,b) then there exists c such that a < x1< b.

Solution 5

Correct option: (b)

 

ϕ(x) is continuous and differentiable function then using statement of Rolle's theorem f(a)=f(b). Hence, here sin 0=0 also sin п=0. The answer is [0,  ].

Solution 6

Correct option: (a)

 

  

Solution 7

Correct option: (a)

  

Solution 8

Correct answer: (c)

 

  

Solution 9

Correct option: (d)

 

  

Solution 10

Correct option: (a)

 

  

Solution 11

Correct option: (d)

 

  

Mean Value Theorems Exercise Ex. 15VSAQ

Solution 1

Solution 2

Solution 3

Solution 4

Solution 5