Intermediate Algebra: Connecting Concepts through Application

Published by Brooks Cole
ISBN 10: 0-53449-636-9
ISBN 13: 978-0-53449-636-4

Chapter 6 - Logarithmic Functions - Chapter Test - Page 543: 4

Answer

$x = \frac{-7+\sqrt {2793}}{4}$

Work Step by Step

$\log_7 x + \log_7 (2x+7) -3 = 0$ $\log_7 x(2x+7)- 3 = 0$ $\log_7 x(2x+7)= 3$ $7^{3} = x(2x+7)$ $343 = 2x^{2} + 7x$ $2x^{2} + 7x - 343 = 0$ $x = \frac{-(7)±\sqrt {7^{2}-4(2)(-343)}}{2(2)}$ $x = \frac{-7±\sqrt {49+2744}}{2(2)}$ $x = \frac{-7±\sqrt {49+2744}}{4}$ $x = \frac{-7±\sqrt {2793}}{4}$ $x = \frac{-7+\sqrt {2793}}{4}$
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