Question

If the mean value theorem is $$f\left( b \right) - f\left( a \right) = \left( {b - a} \right)f'\left( c \right).$$      Then, for the function $${x^2} - 2x + 3$$   in $$\left[ {1,\,\frac{3}{2}} \right]$$  the value of $$c$$ is :

A. $$\frac{6}{5}$$
B. $$\frac{5}{4}$$  
C. $$\frac{4}{3}$$
D. $$\frac{7}{6}$$
Answer :   $$\frac{5}{4}$$
Solution :
$$\eqalign{ & {\text{Let }}f\left( x \right) = {x^2} - 2x + 3 \cr & {\text{Since, }}f'\left( c \right) = \frac{{f\left( {\frac{3}{2}} \right) - f\left( 1 \right)}}{{\frac{3}{2} - 1}}\,\,\,\,\,\,\,\,\left( {{\text{given}}} \right) \cr & \Rightarrow 2c - 2 = \frac{{\frac{9}{4} - \frac{6}{2} + 3 - \left( {1 - 2 + 3} \right)}}{{\frac{3}{2} - 1}} \cr & \Rightarrow c = \frac{5}{4} \cr} $$

Releted MCQ Question on
Calculus >> Continuity

Releted Question 1

For a real number $$y,$$ let $$\left[ y \right]$$ denotes the greatest integer less than or equal to $$y:$$ Then the function $$f\left( x \right) = \frac{{\tan \left( {\pi \left[ {x - \pi } \right]} \right)}}{{1 + {{\left[ x \right]}^2}}}$$     is-

A. discontinuous at some $$x$$
B. continuous at all $$x,$$ but the derivative $$f'\left( x \right)$$  does not exist for some $$x$$
C. $$f'\left( x \right)$$  exists for all $$x,$$ but the second derivative $$f'\left( x \right)$$  does not exist for some $$x$$
D. $$f'\left( x \right)$$  exists for all $$x$$
Releted Question 2

The function $$f\left( x \right) = \frac{{\ln \left( {1 + ax} \right) - \ln \left( {1 - bx} \right)}}{x}$$       is not defined at $$x = 0.$$  The value which should be assigned to $$f$$ at $$x = 0,$$  so that it is continuous at $$x =0,$$  is-

A. $$a-b$$
B. $$a+b$$
C. $$\ln a - \ln b$$
D. none of these
Releted Question 3

The function $$f\left( x \right) = \left[ x \right]\cos \left( {\frac{{2x - 1}}{2}} \right)\pi ,\,\left[ . \right]$$      denotes the greatest integer function, is discontinuous at-

A. all $$x$$
B. All integer points
C. No $$x$$
D. $$x$$ which is not an integer
Releted Question 4

The function $$f\left( x \right) = {\left[ x \right]^2} - \left[ {{x^2}} \right]$$    (where $$\left[ y \right]$$ is the greatest integer less than or equal to $$y$$ ), is discontinuous at-

A. all integers
B. all integers except 0 and 1
C. all integers except 0
D. all integers except 1

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Continuity


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