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Q. 34

Expert-verified
Calculus
Found in: Page 464
Calculus

Calculus

Book edition 1st
Author(s) Peter Kohn, Laura Taalman
Pages 1155 pages
ISBN 9781429241861

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Illustration

Short Answer

Solve x21+x2dx the following two ways:

(a) with the substitution u=tan-1x;

(b) with the trigonometric substitution x = tan u.

Part (a) The solution of the given integral is x-tan-1x+C.

Part (b) The solution of the given integral is x-tan-1x+C.

See the step by step solution

Step by Step Solution

Part (a) Step 1. Given Information.

The given integral is x21+x2dx.

Part (a) Step 2. Solve.

We have to solve the integral with the substitution u=tan-1x, so the derivative is du=11+x2dx.

Let's solve the integral by substituting u,

x21+x2dx=tanu21+tanu21+tanu2du=tan2u du=-1+sec2u du=-1 du +sec2u du=-u+tanu+CSubstitute back u=-tan-1x+x+C=x-tan-1x+C

Part (b) Step 1. Solve.

We have to solve the integral with the substitution x=tanu, so the derivative is dx=sec2u du.

Let's solve the integral by substituting x,

role="math" localid="1648810032401" x21+x2dx=tan2u1+tan2usec2u du=tan2usec2usec2u du 1+tan2u=sec2u=tan2u du=-1+sec2u du=-1 du +sec2u du=-u+tanu+CSubstitute back u=-tan-1x+x+C=x-tan-1x+C

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