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f(a) = g(a) = h(a)

and f(x) <= g(x) <= (x) for all x

Prove g(x) is differentible and that

f'(a) = g'(a) = h'(a).

So.. I need to prove that the following limit exists:

lim h -->0 (g(x+h) - g(x)) / h

but how can i use the fact that f(x) <= g(x) <= (x) for all x?

Thanks

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# Homework Help: Spivak Derivate Question

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