Question

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請問這三小題要怎麼寫⊙﹏⊙

64. Let f be a function that is differentiable at x = c.
noa. Explain why
f(x) – f(c)
f'(c) = lim
X - C
-
X->C

b. Use the result of part (a) together with the fact that
f(x) – f(c)
f(x) - f(c) =
(x - )
c
x - C
to show that
lim [f(x) = f(c)] = 0
XC
c. Explain why the result obtained in part (b)
shows that f is continuous at x = c.

微積分