Discuss the applicability of Rolle’s theorem for the following functions on the indicated intervals :
f(x) = 2x2 – 5x + 3 on [1, 3]
Given function is:
⇒ f(x) = 2x2 – 5x + 3 on [1,3]
Since given function ‘f’ is a polynomial. So, it is continuous and differentiable every where.
Now, we find the values of function at the extremum values.
⇒ f(1) = 2(1)2–5(1) + 3
⇒ f(1) = 2 – 5 + 3
⇒ f(1) = 0 ......(1)
⇒ f(3) = 2(3)2–5(3) + 3
⇒ f(3) = 2(9)–15 + 3
⇒ f(3) = 18 – 12
⇒ f(3) = 6 ......(2)
From (1) and (2), we can say that,
f(1)≠f(3)
∴ Rolle’s theorem is not applicable for the function f in interval [1,3].