The Mean Value Theorem states that if a function is
continuous and differentiable over the closed interval [a,b], then there is a point c,
that belongs to [a,b], such that:
f'(c) = [f(b) -
f(a)]/(b-a)
To calculate f'(c), we'll have to differentiate
the function f(x).
f'(x) =
(x^2+2x-1)'
f'(x) = 2x +
2
Now, we'll substitute x by
c:
f'(c) = 2c + 2
From the
mean value theorem, we'll get:
f'(c) = [f(3) - f(-2)]/(3 +
2)
We'll calculate f(3):
f(3)
= 3^2+2*3-1
f(3) =9+6-1
f(3)
=14
We'll calculate
f(-2):
f(-2) =
(-2)^2+2*(-2)-1
f(-2) = 4 - 4 -
1
We'll eliminate like
terms:
f(-2) = -1
f'(c) =
(14+1)/5
f'(c) = 15/5
f'(c) =
3 (1)
But f'(c) = 2c + 2
(2).
We'll substitute (1) in
(2):
2c + 2 = 3
2c =
3-2
2c = 1
c =
1/2
For x = 1/2, the mean
value theorem is satisfied for the function f(x) =
x^2+2x-1.
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