Verify Rolle’s theorem for each of the following functions:
Condition (1):
Since, f(x)=(x-1)(x-2)2 is a polynomial and we know every polynomial function is continuous for all xϵR.
⇒ f(x)= (x-1)(x-2)2 is continuous on [1,2].
Condition (2):
Here, f’(x)= (x-2)2+2(x-1)(x-2) which exist in [1,2].
So, f(x)= (x-1)(x-2)2 is differentiable on (1,2).
Condition (3):
Here, f(1)= (1-1)(1-2)2=0
And f(2)= (2-1)(2-2)2=0
i.e. f(1)=f(2)
Conditions of Rolle’s theorem are satisfied.
Hence, there exist at least one cϵ(1,2) such that f’(c)=0
i.e. (c-2)2+2(c-1)(c-2)=0
(3c-4)(c-2)=0
i.e. c=2 or c=4÷3
Value of
Thus, Rolle’s theorem is satisfied.