College Algebra (11th Edition)

Published by Pearson
ISBN 10: 0321671791
ISBN 13: 978-0-32167-179-0

Chapter 5 - Section 5.2 - Matrix Solution of Linear Systems - 5.2 Exercises - Page 500: 49

Answer

$A = \frac{1}{2}; B = \frac{1}{2}$

Work Step by Step

The given equation is: $$\dfrac{x}{(x-a)(x+a)} =\dfrac{A}{(x-a)}+\dfrac{B}{(x+a)} ~~~(1)$$ On multiplying equation (1) with $(x-a) (x+a)$, we obtain: $$x =A(x+a)+B(x-a)~~~(2)$$ Now, we will put $x=a$ in equation (2) to eliminate $B$: $$a=A(a+a)\Rightarrow A=\dfrac{1}{2}$$ Next, we will put $x=-a$ in equation (2) to eliminate $A$: $$-a=B(-a-a)\Rightarrow B=\dfrac{1}{2}$$ We got: $$A = \dfrac{1}{2}; B = \dfrac{1}{2}$$
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