Logarithms
Understanding Logarithms
- Logarithms are another way of writing indices.
- The operation of finding a logarithm is the inverse operation to finding a power or exponent.
- The equation y = log_b x means the same as b^y = x.
- For instance, log base 10 of 1000 is three, written as log10 1000 = 3.
Properties of Logarithms
- The Product Rule: log_b(mn) = log_b m + log_b n, this rule signifies that the logarithm of the product of two numbers is the sum of the logarithm of those numbers.
- The Quotient Rule: log_b(m/n) = log_b m - log_b n, this rule means the logarithm of the division of two numbers is the difference of the logarithm of those numbers.
- The Power Rule: log_b(m^n) = n ⋅ log_b m, this rule means the logarithm of a number raised to a power is the product of the power and the logarithm of the number.
Common and Natural Logarithms
- A common logarithm is a logarithm with base 10. It is typically written as, log10 x or simply, log x.
- A natural logarithm has a base e (approximately equal to 2.718). It is denoted as ln i.e., base e logarithm of x is written as ln x.
Changing the Base of Logarithms
- The Change of Base formula allows you to compare logarithms with different bases. The formula is as follows: log_b a = log_c a / log_c b.
- This formula can be particularly useful when dealing with calculators, as they often can only handle base 10 (common logarithm) or base e (natural logarithm).
Solving Logarithmic Equations
- To solve a logarithmic equation, aim to rewrite it in exponential form, or use the properties of logarithms to simplify and solve.
- Remember, only logarithms with the same base can be combined.