Question:

The value of the integral $I=\int\limits^{6}_{{3}}$$\frac{\sqrt{x}}{\sqrt{9-x}+\sqrt{x}}dx$ is :

Updated On: Jul 27, 2022
  • $\frac{3}{2}$
  • $2$
  • $1$
  • $\frac{1}{2}$
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The Correct Option is A

Solution and Explanation

Let $I=\int\limits^{6}_{{3}}$$\frac{\sqrt{x}}{\sqrt{9-x}+\sqrt{x}}dx ...\left(i\right)$ $=\int\limits^{6}_{{3}}$$\frac{\sqrt{9-x}}{\sqrt{9-9+x}+\sqrt{9-x}}dx$ $\Rightarrow$ $I=\int\limits^{6}_{{3}}$ $\frac{\sqrt{9-x}}{\sqrt{x}+\sqrt{9-x}}dx ...\left(ii\right)$ On adding Eqs. (i) and (ii), we get $2I=\int\limits^{6}_{{3}}$$\frac{\sqrt{x}+\sqrt{9-x}}{\sqrt{x}+\sqrt{9-x}}dx$ $=\int\limits^{6}_{{3}}$$1\,dx=\left[x\right]_{3}^{6}$ $=6-3=3$ $\Rightarrow I=\frac{3}{2}$
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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.