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VCE 11 Methods 2023

7.08 Properties of logarithms

Worksheet
Rewrite logarithmic expressions
1

Simplify each of the following expressions in exact form:

a

\log 4 + \log 9

b

\log_{10} \left(10\right) + \log_{10} \left(10\right)

c

\log_{10} 11 + \log_{10} 2 + \log_{10} 9

d

\log_{10} 12 - \left(\log_{10} 2 + \log_{10} 3\right)

e

\log_{10} 5 + \log_{10} 7 - \log_{10} 3

f

\dfrac{\log_{10} 4}{\log_{10} 2}

g

\dfrac{\log_{4} 125}{\log_{4} 5}

h

\dfrac{\log a^{8}}{\log a^{4}}

i

\dfrac{\log a^{3}}{\log \sqrt[3]{a}}

j

\dfrac{\log \left(\dfrac{1}{x^{4}}\right)}{\log x}

k

\log_{10} 10 + \dfrac{\log_{10} \left(15^{20}\right)}{\log_{10} \left(15^{5}\right)}

l

\dfrac{8 \log_{10} \left(\sqrt{10}\right)}{\log_{10} \left(100\right)}

m

10^{\log w}

n

\log 10 x + \log 10 y

o

x^{ 4 \log_{x} 3 - 6 \log_{x} 2}

2

Rewrite the following as the sum or difference of logarithms without any powers, fractions or surds:

a

\log_{9} u v

b

\log \left(x^{4}\right)

c

\log_{4} \left(x^{7}\right)

d
\log_{5} \left(\dfrac{9}{7}\right)
e

\log \left(x^{\frac{2}{5}}\right)

f
\log_{b} \left(x^{2}\right)
g

\log \left( 3 x^{ - 1 }\right)

h

\log \left(\left( 3 x\right)^{5}\right)

i

\log \left( 7 x^{ - 4 }\right)

j

\log \left(\left( 5 x\right)^{ - 7 }\right)

k

\log \left(\left( 2 x\right)^{ - 1 }\right)

l

\log \left(\dfrac{1}{x y}\right)

m
\log \left(\dfrac{p q}{r}\right)
n

\log \left(\left( 3 x + 7\right)^{ - 1 }\right)

o

\log \left(\left( 3 x + 4\right)^{ - 8 }\right)

p

\log \left(\left( 5 x + 7\right)^{\frac{1}{2}}\right)

q

\log \left(\left( 5 x + 2\right)^{6}\right)

r

\log \left(\left(x + 6\right)^{5}\right)

s

\log_{2} \left(5x\right)

t
\log_{10} \left(\dfrac{2}{x}\right)
u

\log \left(m^{2}\right)

v

\log \left( 5 x^{\frac{2}{3}}\right)

w

\log \left(\left( 14 x\right)^{\frac{1}{3}}\right)

x

\log \left(\sqrt{\dfrac{c^{8}}{d}}\right)

3

Write each of the following as a single logarithm or integer:

a

5 \log x^{3} - 4 \log x^{2}

b

5 \log x + 3 \log y

c

8 \log x - \dfrac{1}{3} \log y

d

7 \log x - \log \left(\dfrac{1}{x}\right) - \log y

e

7 \log_{10} 5 - 21 \log_{10} 25

f

5 \log_{10} 8 - 3 \log_{10} 4

g

2 \log_{6} 3 + \dfrac{1}{3} \log_{6} 64

h

\log_{2} 36 - 2 \log_{2} 3

4

Rewrite the expression \log x^{2} + \log x^{3} in the form k \log x.

5

Rewrite the following in terms of base 10 logarithms:

a

\log_{4} 16

b

\log_{3} 0.9

c

\log_{3} \sqrt{5}

6

Rewrite \log_{3} 20 in terms of base 4 logarithms.

Evaluate logarithmic expressions
7

For each of the following logarithmic expressions:

i

Rewrite the expression in terms of base 10 logarithms.

ii

Hence, evaluate each to two decimal places.

a
\log_{8} 21
b
\log_{4} \sqrt{5}
c
\log_{2} 3^{3}
d
\log_{\pi} 105
8

Simplify and evaluate each of the following expressions:

a

\dfrac{5 \log m^{2}}{6 \log \sqrt[3]{m}}

b

\dfrac{\log a^{8}}{\log a^{4}}

c

\dfrac{\log a^{3}}{\log \sqrt[3]{a}}

d

\dfrac{\log \left(\dfrac{1}{x^{4}}\right)}{\log x}

e

\dfrac{\log_{10} 4}{\log_{10} 2}

f

\dfrac{\log_{4} 125}{\log_{4} 5}

g

\log_{10} 10 + \dfrac{\log_{10} \left(15^{20}\right)}{\log_{10} \left(15^{5}\right)}

h

\dfrac{8 \log_{10} \left(\sqrt{10}\right)}{\log_{10} \left(100\right)}

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Outcomes

U2.AoS1.17

the key features and properties of the exponential functions, logarithmic functions and their graphs, including any vertical or horizontal asymptotes

U2.AoS1.18

the relationship between an exponential function to a given base and the logarithmic function to the same base as inverse functions

U2.AoS2.1

use of inverse functions and transformations to solve equations of the form Af(nx)+c, and f is sine, cosine, tangent or a^x, using exact or approximate values on a given domain

U2.AoS2.2

exponent laws and logarithm laws, including their application to the solution of simple exponential equations

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