Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 13 - Conic Sections - 13.2 Conic Sections: Ellipses - 13.2 Exercise Set - Page 862: 39

Answer

$x_1=2$ $x_2=-0.75$

Work Step by Step

Let's solve $\dfrac{4}{x+2}+\dfrac{3}{2x-1}=2$. Let's find common denominator. $$\dfrac{4(2x-1)+3(x+2)}{(x+2)(2x-1)}=2$$ $$4(2x-1)+3(x+2)=2(x+2)(2x-1)$$ $$8x-4+3x+6=2(2x^2-x+4x-2)$$ $$8x-4+3x+6=4x^2+6x-4$$ $$11x+2=4x^2+6x-4$$ $$4x^2-5x-6=0$$ Let's find the discriminant. The quadratic equation in its standard form is $$ax^2+bx+c=0.$$ $D=b^2−4ac.$ In our case $D=25-4\cdot(-6)\cdot4=121>0.$ So we have two solutions. $$x_1=\dfrac{−b+\sqrt D}{2a}=\dfrac{5+11}{8}=2$$ $$x_2=\dfrac{−b−\sqrt D}{2a}=\dfrac{5-11}{8}=-\dfrac{6}{8}=-\dfrac{3}{4}=-0.75$$ As none of the solutions is a zero of the denominator of the given equation, it means both solutions are correct.
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