College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 5, Systems of Equations and Inequalities - Section 5.3 - Partial Fractions - 5.3 Exercises - Page 462: 18

Answer

$\frac{x-12}{x(x-4)}=\frac{3}{x}+\frac{-2}{x-4}$

Work Step by Step

$\frac{x-12}{(x^2-4x)}$, factorising $x^2-4x=x(x-4)$: $\frac{x-12}{x(x-4)}=\frac{A}{x}+\frac{B}{x-4}$, $x-12=A(x-4)+B(x)$, $x-12=Ax-4A+Bx$, $x-12=(A+B)x-4A$, $(A+B)x=x$, $A+B=1$ and $-4A=-12, A=3$: $A=3$, substituting back into the equation, $3+B=1, B=-2$ thus, $\frac{x-12}{x(x-4)}=\frac{3}{x}+\frac{-2}{x-4}$
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