Mean Value Theorem: Find Point [1,4]

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Homework Statement



State the Mean Value Theorem and find a point which satisfies the conclusions of the Mean Value Theorem for f(x)=(x-1)3 on the interval [1,4].

2. The attempt at a solution

Mean Value Theorem:states that there exists a c∈(a,b) such that f'(c)=[itex]\frac{f(b)-f(a)}{b-a}[/itex]

3(x-1)2=[itex]\frac{27-0}{4-1}[/itex]

3(x-1)2=[itex]\frac{27}{3}[/itex]

3(x-1)2=9

→(x-1)2=3

→x=1±√3

∴x=1+√3 which lies on the interval [1,4].

I was wondering if I did the question correctly and if there was anything further I should add.
 
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This is all good. Almost. You need to state certain conditions for f(x) and verify that the given f(x) meets them.
 
What 'certain condition' are we talking about here?
 
The hypothesis of the MVT; that f is continuous on the interval and differentiable every in the interior of the interval.