Verify mean value theorem for each of the functions given
Given:
Now, we have to show that f(x) verify the Mean Value Theorem
First of all, Conditions of Mean Value theorem are:
a) f(x) is continuous at (a,b)
b) f(x) is derivable at (a,b)
If both the conditions are satisfied, then there exist some ‘c’ in (a,b) such that
Condition 1:
Firstly, we have to show that f(x) is continuous.
Here, f(x) is continuous because f(x) has a unique value for each x ∈ [1,5]
Condition 2:
Now, we have to show that f(x) is differentiable
[using chain rule]
∴ f’(x) exists for all x ∈ (1,5)
So, f(x) is differentiable on (1,5)
Hence, Condition 2 is satisfied.
Thus, mean value theorem is applicable to given function.
Now,
Now, we will find f(a) and f(b)
so, f(a) = f(1)
and f(b) = f(5)
Now, let us show that c ∈ (1,5) such that
On differentiating above with respect to x, we get
Put x = c in above equation, we get
By Mean Value theorem,
Squaring both sides, we get
⇒ 16c2 = 24 × (25 – c2)
⇒ 16c2 = 600 – 24c2
⇒ 24c2 + 16c2 = 600
⇒ 40c2 = 600
⇒ c2 = 15
⇒ c = √15 ∈ (1,5)
Hence, Mean Value Theorem is verified.