Logarithmic Functions - AP Precalculus
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What is the simplified form of $\text{log}_b(b^x)$?
What is the simplified form of $\text{log}_b(b^x)$?
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$x$. Logarithm and exponential with same base cancel out.
$x$. Logarithm and exponential with same base cancel out.
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What is $\text{log}_{10}(100)$?
What is $\text{log}_{10}(100)$?
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- Since $10^2 = 100$, the answer is 2.
- Since $10^2 = 100$, the answer is 2.
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Find $x$ if $\text{log}_3(x) = 4$.
Find $x$ if $\text{log}_3(x) = 4$.
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- Convert to exponential: $3^4 = 81$.
- Convert to exponential: $3^4 = 81$.
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Find the value of $\text{log}_7(49)$.
Find the value of $\text{log}_7(49)$.
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- Since $7^2 = 49$, the answer is 2.
- Since $7^2 = 49$, the answer is 2.
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What does $\text{log}_b(0)$ evaluate to?
What does $\text{log}_b(0)$ evaluate to?
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Undefined. Logarithm of zero does not exist in real numbers.
Undefined. Logarithm of zero does not exist in real numbers.
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Simplify $\text{log}_a(a^5)$.
Simplify $\text{log}_a(a^5)$.
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- Logarithm and exponential with same base cancel out.
- Logarithm and exponential with same base cancel out.
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What is the simplified form of $\text{log}_b(b^x)$?
What is the simplified form of $\text{log}_b(b^x)$?
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x. Logarithm and exponential with same base cancel out.
x. Logarithm and exponential with same base cancel out.
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Convert $\text{ln}(e^3)$ to a simpler form.
Convert $\text{ln}(e^3)$ to a simpler form.
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- Natural log and $e$ with same exponent cancel out.
- Natural log and $e$ with same exponent cancel out.
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Simplify $\log_a(a^5)$.
Simplify $\log_a(a^5)$.
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- Logarithm and exponential with same base cancel out.
- Logarithm and exponential with same base cancel out.
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Express the exponential form of $\text{log}_5(125) = 3$.
Express the exponential form of $\text{log}_5(125) = 3$.
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$5^3 = 125$. Direct conversion from logarithmic to exponential form.
$5^3 = 125$. Direct conversion from logarithmic to exponential form.
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What is the value of $\text{log}_a(a)$?
What is the value of $\text{log}_a(a)$?
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- Any base raised to power 1 equals itself.
- Any base raised to power 1 equals itself.
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Express $\text{log}_b(a^n)$ using the power rule.
Express $\text{log}_b(a^n)$ using the power rule.
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$n \times \text{log}_b(a)$. Power rule moves exponent $n$ as coefficient.
$n \times \text{log}_b(a)$. Power rule moves exponent $n$ as coefficient.
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What is $\text{log}_b(b^0)$?
What is $\text{log}_b(b^0)$?
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- Since $b^0 = 1$ and $\text{log}_b(1) = 0$.
- Since $b^0 = 1$ and $\text{log}_b(1) = 0$.
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Simplify $\text{log}_b(\frac{b^2}{b^3})$.
Simplify $\text{log}_b(\frac{b^2}{b^3})$.
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-1. Quotient simplifies to $b^{-1}$, so $\text{log}_b(b^{-1}) = -1$.
-1. Quotient simplifies to $b^{-1}$, so $\text{log}_b(b^{-1}) = -1$.
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What does $\text{ln}(e)$ equal?
What does $\text{ln}(e)$ equal?
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- Natural log of its own base equals 1.
- Natural log of its own base equals 1.
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Find the value of $\text{log}_7(49)$.
Find the value of $\text{log}_7(49)$.
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- Since $7^2 = 49$, the answer is 2.
- Since $7^2 = 49$, the answer is 2.
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Express $\text{log}_b(\frac{1}{x})$ using logarithm rules.
Express $\text{log}_b(\frac{1}{x})$ using logarithm rules.
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$-\text{log}_b(x)$. Reciprocal creates negative exponent, so negative log.
$-\text{log}_b(x)$. Reciprocal creates negative exponent, so negative log.
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What is $\text{ln}(1)$?
What is $\text{ln}(1)$?
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- Natural log of 1 equals 0 since $e^0 = 1$.
- Natural log of 1 equals 0 since $e^0 = 1$.
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Convert $\text{log}_b(\frac{x}{y})$ using the quotient rule.
Convert $\text{log}_b(\frac{x}{y})$ using the quotient rule.
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$\text{log}_b(x) - \text{log}_b(y)$. Quotient rule expands division into subtraction of logs.
$\text{log}_b(x) - \text{log}_b(y)$. Quotient rule expands division into subtraction of logs.
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Express $e^{\text{ln}(x)}$ in simpler form.
Express $e^{\text{ln}(x)}$ in simpler form.
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x. Exponential and natural log are inverse functions.
x. Exponential and natural log are inverse functions.
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Evaluate $\text{log}_{10}(0.1)$.
Evaluate $\text{log}_{10}(0.1)$.
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-1. Since $10^{-1} = 0.1$, the answer is -1.
-1. Since $10^{-1} = 0.1$, the answer is -1.
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If $f(x) = \text{log}_b(x)$, find $f(b^4)$.
If $f(x) = \text{log}_b(x)$, find $f(b^4)$.
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- Logarithm and exponential with same base cancel out.
- Logarithm and exponential with same base cancel out.
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Determine the range of $f(x) = \text{log}_b(x)$.
Determine the range of $f(x) = \text{log}_b(x)$.
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All real numbers. Logarithms can output any real value as input approaches 0 or infinity.
All real numbers. Logarithms can output any real value as input approaches 0 or infinity.
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Express $\text{log}_b(x^3)$ using the power rule.
Express $\text{log}_b(x^3)$ using the power rule.
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$3 \times \text{log}_b(x)$. Power rule moves the exponent as a coefficient.
$3 \times \text{log}_b(x)$. Power rule moves the exponent as a coefficient.
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What is $\text{log}_3(1)$?
What is $\text{log}_3(1)$?
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- Any base raised to the power 0 equals 1.
- Any base raised to the power 0 equals 1.
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Solve for $x$: $\text{log}_4(64) = x$.
Solve for $x$: $\text{log}_4(64) = x$.
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- Since $4^3 = 64$, the answer is 3.
- Since $4^3 = 64$, the answer is 3.
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Convert $\text{ln}(e^3)$ to a simpler form.
Convert $\text{ln}(e^3)$ to a simpler form.
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- Natural log and $e$ with same exponent cancel out.
- Natural log and $e$ with same exponent cancel out.
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Express $10^x = 1000$ in logarithmic form.
Express $10^x = 1000$ in logarithmic form.
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$\text{log}_{10}(1000) = x$. Direct conversion from exponential to logarithmic form.
$\text{log}_{10}(1000) = x$. Direct conversion from exponential to logarithmic form.
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Find $\text{log}_b(b^x)$.
Find $\text{log}_b(b^x)$.
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x. Logarithm and exponential with same base cancel out.
x. Logarithm and exponential with same base cancel out.
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Simplify $\text{log}_b(1)$.
Simplify $\text{log}_b(1)$.
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- Any base raised to the power 0 equals 1.
- Any base raised to the power 0 equals 1.
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