College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 6 - Review Exercises - Page 500: 44

Answer

$x=-0.3976$

Work Step by Step

$9^x+4\times3^x-3=0,$ $3^{2x}+4\times3^x-3=0,$ Let's let $k=3^x,$ $k^2+4k-3=0,$ Solving the quadratic equation using te quadratic formula, $k=\frac{-b\pm \sqrt{b^2-4ac}}{2a}.$ $k=\frac{-4\pm \sqrt{(4)^2-4(1)(-3)}}{2(1)}=-2\pm\sqrt{7},$ $k_1=-2-\sqrt 7<0$ or $k=-2+\sqrt 7\approx 0.6458$ Therefore, $3^x=0.6458,$ $x\log3=\log(0.6458),$ $x=\frac{\log(0.6458)}{\log3}\approx -0.3976$
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