Question:

$\displaystyle\int_{1/2}^{2}|\log_{10}\,x|dx= $

Updated On: Jul 6, 2022
  • $\log_{10}\left(\frac{8}{e}\right) $
  • $\frac{1}{2}\log_{10}\left(\frac{8}{e}\right) $
  • $log_{10}\left(\frac{2}{e}\right) $
  • none of these.
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The Correct Option is B

Solution and Explanation

$\int log \, x \, dx=x \,log x-x$ [By Using integration by parts] $log x is -ve. for x, < 1$ and $+ve$ for $x > 1 $. Also $log_{10} \,x= \frac{log\,x}{log\,10}$ $\therefore$ given integral $=\frac{1}{log\,10}\left[\int\limits_{1 /2}^{1}-log\,x\,dx+\int\limits_{1}^{2} log\,x\,dx\right]$ $=-\frac{1}{log\,10} \left[x\,log\,x-x\right]_{1 /2}^{1}+\frac{1}{log\,10} \left[x\,log\,x-x\right]_{1}^{2}$ $=-\frac{1}{log\,10}\left[-1-\frac{1}{2}log\frac{1}{2}+\frac{1}{2}\right]+\frac{1}{log\,10} \left[2\,log\,2-2+1\right]$ $=\frac{1}{log\,10}\left[\frac{1}{2}-\frac{1}{2}log\,2\right]+\frac{2\,log\,2-1}{log\,10}$ $=\frac{4\,log\,2-2+1-log\,2}{2\,log\,10}=\frac{3\,log\,2-1}{2\,log\,10}$ $=\frac{1}{2} \frac{log\,8-log\,e}{log\,10}=\frac{1}{2} \frac{log\left(\frac{8}{e}\right)}{log\,10}$ $=\frac{1}{2}log_{10} \left(\frac{8}{e}\right)$
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Concepts Used:

Integral

The representation of the area of a region under a curve is called to be as integral. The actual value of an integral can be acquired (approximately) by drawing rectangles.

  • The definite integral of a function can be shown as the area of the region bounded by its graph of the given function between two points in the line.
  • The area of a region is found by splitting it into thin vertical rectangles and applying the lower and the upper limits, the area of the region is summarized.
  • An integral of a function over an interval on which the integral is described.

Also, F(x) is known to be a Newton-Leibnitz integral or antiderivative or primitive of a function f(x) on an interval I.

F'(x) = f(x)

For every value of x = I.

Types of Integrals:

Integral calculus helps to resolve two major types of problems:

  1. The problem of getting a function if its derivative is given.
  2. The problem of getting the area bounded by the graph of a function under given situations.