Let a function ƒ : [0, 5] $\to$ R be continuous,
ƒ(1) = 3 and F be defined as :
$F(x) = \int\limits_1^x {{t^2}g(t)dt}$ , where $g(t) = \int\limits_1^t {f(u)du}$
Then for the function F, the point x = 1 is :
Solution
$F(x) = \int\limits_1^x {{t^2}g(t)dt}$
<br><br>$\Rightarrow$ F'(x) = x<sup>2</sup>g(x) = x<sup>2</sup>$\int\limits_1^t {f(u)du}$
<br><br>$\therefore$ F'(1) = (1)(0) = 0
<br><br>Now, F''(x) = 2xg(x) + x<sup>2</sup>g'(x)
<br><br>F''(1) = 2g(1) + g'(1) = 0 + g'(1) = 3
<br><br>[ As g'(t) = f(t); g'(1) = f'(1) = 3 ]
<br><br>So, at x = 1, F'(1) = 0 and F"(1) = 3 > 0
<br><br>$\therefore$ For the function f(x), x = 1 is a point of local minima.
About this question
Subject: Mathematics · Chapter: Definite Integration · Topic: Properties of Definite Integrals
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