Differential Equations and Linear Algebra (4th Edition)

Published by Pearson
ISBN 10: 0-32196-467-5
ISBN 13: 978-0-32196-467-0

Chapter 5 - Inner Product Spaces - 5.3 The Gram-Schmidt Process - Problems - Page 366: 18

Answer

See below

Work Step by Step

We are given: $f_1(x)=1\\ f_2(x)=x\\ f_3(x)=x^4\\ a=0\\ b=1$ According to Gram-Schmidt we have: $v_1=f_1(x)=1\\ v_2=f_2(x)-\frac{(f_2(x),v_1)}{||v_1||^2}v_1\\ =x-\frac{(x,1)}{||1||^2}1 \\ =x-\frac{\int ^1_0 x.1dx}{\int^1_0dx}.1\\ =x-\frac{ \frac{x^2}{2}|^1_0}{x|^1_0} \\ =x-\frac{\frac{1}{2}}{1}\\ =x-\frac{1}{2}\\ v_3=f_3(x)-\frac{(f_3(x),v_1)}{||v_1||^2}v_1-\frac{(f_3(x),v_2)}{||v_2||^2}v_2\\ =x^2-\frac{(x^2,1)}{||1||^2}1- \frac{(x^2,x-\frac{1}{2})}{||x-\frac{1}{2}||^2}(x-\frac{1}{2})\\ =x^2-\frac{\int ^1_0 x^2.1dx}{\int^1_0dx}-\frac{\int ^1_0 x^2(x-\frac{1}{2})dx}{\int^1_0(x-\frac{1}{2})^2dx}(x-\frac{1}{2})\\ =x^2-\frac{1}{3}-\frac{ \frac{x^4}{4}-\frac{x^3}{6}|^1_0}{\frac{x^3}{3}-\frac{x^2}{2}+\frac{x}{4}|^1_0}(x-\frac{1}{2}) \\ =x^2-\frac{1}{3}-\frac{\frac{1}{12}}{\frac{1}{12}}(x-\frac{1}{2})\\ =x^2-\frac{1}{3}-x+\frac{1}{2} \\ =x^2-x+\frac{1}{6}$ Hence, an orthogonal basic spanned by the given factors is: $\{1,x-\frac{1}{2},x^2-x+\frac{1}{6}\}$
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