Change the following logarithmic expressions.
\log_2\left(3x\right)-\log_2\left(6x\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(x\right)-\log_a\left(y\right)=\log_a\left(\dfrac{x}{y}\right)
Applying this formula to our problem:
\log_2\left(3x\right)-\log_2\left(6x\right)=\log_2\left(\dfrac{3x}{6x}\right)=\log_2\left(\dfrac{3}{6}\right)=\log_2\left(\dfrac{1}{2}\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem:
2^{c}=\dfrac{1}{2}
Since:
\dfrac{1}{2}=2^{-1}
We conclude that:
\log_2\left(\dfrac{1}{2}\right)=-1
\log_2\left(3x\right)-\log_2\left(6x\right)=-1
\log_3\left(9x^{2}\right)-\log_3\left(3x^{2}\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(x\right)-\log_a\left(y\right)=\log_a\left(\dfrac{x}{y}\right)
Applying this formula to our problem:
\log_3\left(9x^{2}\right)-\log_3\left(3x^{2}\right)=\log_3\left(\dfrac{9x^{2}}{3x^{2}}\right)=\log_3\left(3\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem:
3^{c}=3
Since:
3=3^{1}
We conclude that:
\log_3\left(3\right)=1
\log_3\left(9x^{2}\right)-\log_3\left(3x^{2}\right)=1
\log_5\left(\sqrt[3]{625 m^{2}}\right)-\log_5\left(\sqrt[3]{25 m^{2}}\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(x\right)-\log_a\left(y\right)=\log_a\left(\dfrac{x}{y}\right)
Applying this formula to our problem:
\log_5\left(\sqrt[3]{625 m^{2}}\right)-\log_5\left(\sqrt[3]{25 m^{2}}\right)=\log_5\left(\dfrac{\sqrt[3]{625 m^{2}}}{\sqrt[3]{25 m^{2}}}\right)=\log_5\left(\sqrt[3]{25}\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem:
5^{c}=\sqrt[3]{25}
Since:
\sqrt[3]{25}=5^{\frac{2}{3}}
We conclude that:
\log_5\left(\sqrt[3]{25}\right)=\dfrac{2}{3}
\log_5\left(\sqrt[3]{625 m^{2}}\right)-\log_5\left(\sqrt[3]{25 m^{2}}\right)=\dfrac{2}{3}
\ln\left(x^{2}\right)-\ln\left(ex^{2}\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(x\right)-\log_a\left(y\right)=\log_a\left(\dfrac{x}{y}\right)
Applying this formula to our problem:
\ln\left(x^{2}\right)-\ln\left(ex^{2}\right)=\ln\left(\dfrac{x^{2}}{ex^{2}}\right)=\ln\left(\dfrac{1}{e}\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem:
e^{c}=\dfrac{1}{e}
Since:
\dfrac{1}{e}=e^{-1}
We conclude that:
\ln\left(\dfrac{1}{e}\right)=-1
\ln\left(x^{2}\right)-\ln\left(ex^{2}\right)=-1
\log_2\left(\dfrac{8}{7}\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(\dfrac{x}{y}\right)=\log_a\left(x\right)-\log_a\left(y\right)
Applying this formula to our problem:
\log_2\left(\dfrac{8}{7}\right)=\log_2\left(8\right)-\log_2\left(7\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem, when calculating \log_2\left(8\right) :
2^{c}=8
Since:
8=2^{3}
We conclude that:
\log_2\left(8\right)=3
\log_2\left(\dfrac{8}{7}\right)=3-\log_2\left(7\right)
\ln\left(\dfrac{3}{e^{2}}\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(\dfrac{x}{y}\right)=\log_a\left(x\right)-\log_a\left(y\right)
Applying this formula to our problem:
\ln\left(\dfrac{3}{e^{2}}\right)=\ln\left(3\right)-\ln\left(e^{2}\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem, when calculating \ln\left(e^{2}\right) :
e^{c}=e^{2}
Since:
e^{2}=e^{2}
We conclude that:
\ln\left({e^{2}}\right)=2
\ln\left(\dfrac{3}{e^{2}}\right)=\ln\left(3\right)-2
\log\left(\dfrac{\sqrt[4]{100}}{7}\right)
The formula for a difference of logarithms with the same base is:
\log_a\left(\dfrac{x}{y}\right)=\log_a\left(x\right)-\log_a\left(y\right)
Applying this formula to our problem:
\log\left(\dfrac{\sqrt[4]{100}}{7}\right)=\log\left(\sqrt[4]{100}\right)-\log\left(7\right)
When calculating \log_a\left(b\right), we are looking for a real number c so that:
a^{c}=b
In our problem, when calculating \log\left(\sqrt[4]{100}\right) :
10^{c}=\sqrt[4]{100}
Since:
\sqrt[4]{100}=10^{\frac{2}{4}}=10^{\frac{1}{2}}
We conclude that:
\log\left(\sqrt[4]{100}\right)=\dfrac{1}{2}
\log\left(\dfrac{\sqrt[4]{100}}{7}\right)=\dfrac{1}{2}-\log\left(7\right)