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Need solution for RD Sharma maths Class 12 Chapter 19 Definite Integrals Exercise 19.4 (b) Question 20 textbook solution.

Answers (1)

Answer:- 3

Hints:-  You must know about the rules of integration.

Given:-  \int_{2}^{8} \frac{\sqrt{10-x}}{\sqrt{x}+\sqrt{10-x}} d x

Solution : \int_{2}^{8} \frac{\sqrt{10-x}}{\sqrt{x}+\sqrt{10-x}} d x                                      ....(1)

Then , I=\int_{2}^{8} \frac{\sqrt{10-(2+8-x)}}{\sqrt{2+8-x}+\sqrt{10-(2+8-x)}} d x \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \quad\left[\because \int_{a}^{b} f(x) d x=\int_{a}^{b} f(a+b-x) d x\right]

I=\int_{2}^{8} \frac{\sqrt{x}}{\sqrt{10-x}+\sqrt{x}} d x                                             ...(2)

Adding (1) and (2)

\begin{aligned} &2 I=\int_{2}^{8} \frac{\sqrt{10-x}+\sqrt{x}}{\sqrt{x}+\sqrt{10-x}} d x \\ &2 I=\int_{2}^{8} 1 \cdot d x \\ &2 I=[x]_{2}^{8} \end{aligned}

\begin{aligned} &2 I=[8-2] \\ &I=\frac{6}{2} \\ &I=3 \end{aligned}

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