Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 4 - Section 4.3 - Logarithmic Functions - 4.3 Exercises - Page 352: 55

Answer

$y=\log_9{x}$

Work Step by Step

The graph contains the point $(3, \frac{1}{2})$. This means that the x and y-coordinates of this point satisfy the equation $y=\log_a{x}$. Substitute the x and y values into the given equation to obtain: $\frac{1}{2} = \log_a{3}$ RECALL: $y=\log_a{x} \longrightarrow a^y=x$ Use the rule above to obtain: $\frac{1}{2} = \log_a{3} \longrightarrow a^{\frac{1}{2}} = 3$ Square both sides to obtain: $(a^{\frac{1}{2}})^2=3^2 \\(a^{\frac{1}{2}})^2=9$ Use the rule $(a^m)^n = a^{mn}$ to obtain: $a^{\frac{1}{2} \cdot 2} = 9 \\a^1 = 9 \\a=9$ Thus, the equation of the function whose graph is given is $y=\log_9{x}$.
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