CBSE Class 12-science Answered
Verify Rolle’s theorem for the function f (x) =
on [– 2, 2].

Asked by Topperlearning User | 04 Aug, 2014, 03:32: PM
Clearly, f (x) is defined for all x Î [– 2, 2] and has a unique value for each x Î [– 2, 2]. So, at each point of [–2, 2], the limit of f (x) is equal to the value of the function. Therefore, f (x) is continuous on [–2, 2].
Also, f ¢ (x) =
exists for all x Î (–2, 2)

So, f (x) is differentiable on (–2, 2)
Also, f (–2) = f (2) = 0
Thus, all the three conditions of Rolle’s theorem are satisfied.
Now we have to show that there exists c Î (–2, 2) such that f ¢ (c) = 0
We have,
f (x) =
Þ f ¢ (x) = 


\ f ¢ (x) = 0 Þ
= 0 Þ x = 0

Since c = 0 Î (– 2, 2) such that f ¢ (c) = 0
Hence, Rolle’s theorem is verified.
Answered by | 04 Aug, 2014, 05:32: PM
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