College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 5 - Systems of Equations and Inequalities - Exercise Set 5.3 - Page 549: 9

Answer

$\displaystyle \frac{x}{(x-3)(x-2)}=\frac{3}{x-3}-\frac{2}{x-2}$

Work Step by Step

Both factors of th$e$ denominator are distinct linear factors... see p.541. Decomposition with Distinct Linear Factors In the Denominator: Include one partial fraction with a $constant$ numerator for each distinct linear factor in the denominator. Setup: $\displaystyle \frac{x}{(x-3)(x-2)}=\frac{A}{x-3}+\frac{B}{x-2}\quad /\times(x-3)(x-2)\quad$ ... multipliy with the LCD ... $x=A(x-2)+B(x-3)$ $ x=Ax-2A+Bx-3B\qquad$ /group like terms... $x+0=x(A+B)+(-2A-3B)$ Emphasize the 0 constant term on the LHS, as we now equate the coefficients of like powers of x... $\left\{\begin{array}{l} 1=A+B\\ 0=-2A-3B \end{array}\right.\qquad $solve the system Multiply equation 1. with 3 and add the equations: $3+0=3A-2A+3B-3B$ $3=A$ back substitute: $1=3+B$ $B=-2$ Rewrite the setup decomposition with $A=3, B=-2$ $\displaystyle \frac{x}{(x-3)(x-2)}=\frac{3}{x-3}-\frac{2}{x-2}$
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