BITSAT2014MathematicsContinuity and DifferentiabilityActual
Let f(x)= array c (x-1) 1 x-1 if x 1 0 if x=1 array . Then which one of the following is true?
Options
- Af is differentiable at x=0 and x=1
- Bf is differentiable at x=0 but not at x=1
- Cf is differentiable at x=1 but not at x=0
- Df is neither differentiable at x=0 nor at x=1
Correct answer
B. f is differentiable at x=0 but not at x=1
Step-by-step solution
We have; f(x)= array ll (x-1) ( 1 x-1 ) & if x 1 0 & if x=1 array .R f^ (1)= _ h 0 f(1+h)-f(1) h = _ h 0 h 1 h -0 h = _ h 0 1 h which does not exist. f is not differentiable at x=1 Also .f^ (0)= 1 (x-1) - x-1 (x-1)² ( 1 x-1 ) ]_ x=0 =- 1+ 1 f is differentiable at x=0