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If f is a real­-valued differentiable function satisfying  

\left | f\left ( x \right ) -f\left ( y \right )\right |\leq \left ( x-y \right )^{2},x,y \in R and f\left ( 0 \right )= 0 then f\left ( 1 \right ) equals

  • Option 1)

    1

  • Option 2)

    2

  • Option 3)

    0

  • Option 4)

    -1

 

Answers (1)

best_answer

As we learnt in 

Differentiability -

Let  f(x) be a real valued function defined on an open interval (a, b) and  x\epsilon (a, b).Then  the function  f(x) is said to be differentiable at   x_{\circ }   if

\lim_{h\rightarrow 0}\:\frac{f(x_{0}+h)-f(x_{0})}{(x_{0}+h)-x_{0}}


or\:\:\:\lim_{h\rightarrow 0}\:\frac{f(x)-f(x_{0})}{x-x_{0}}

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 \lim_{x\rightarrow y}\frac{\left | f\left ( x \right )-f\left ( y \right ) \right |}{\left | x-y \right |}\leq \lim_{x\rightarrow y}\left | x-y \right |

\Rightarrow \left | f{}'\left ( y \right ) \right |\leq 0 \Rightarrow f{}'\left ( y \right )=0

\Rightarrow f\left ( y \right )= constant

Since f\left ( 0 \right )=0

\therefore f\left ( y \right )=0

Hence f\left ( 1 \right )=0


Option 1)

1

Incorrect option

Option 2)

2

Incorrect option

Option 3)

0

Correct option

Option 4)

-1

Incorrect option

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