Exponential Functions Graphical Representation

This page focuses on the graphical representation of exponential functions, which take the form y = a^x. The shape of the graph depends on the value of the base a.

For a > 1, the function is increasing, with the graph rising from left to right. For 0 < a < 1, the function is decreasing, with the graph falling from left to right. In both cases, the domain of the function is all real numbers $R$.

Highlight: The y-axis $x = 0$ is always an asymptote for exponential functions.

Example: The graph of y = 2^x is an increasing exponential function, while y = $1/2$^x is a decreasing exponential function.

These graphical representations help visualize the behavior of exponential functions and their key properties.

Logarithms: Definition and Properties

This page introduces the concept of logarithms and their fundamental properties. Logarithms are defined as the inverse operation of exponentiation.

Definition: The logarithm of a number b with base a, written as log_a b, is the exponent to which a must be raised to produce b.

The page outlines the conditions for logarithms: a > 0, a ≠ 1, and b > 0. It also introduces special logarithms such as the natural logarithm $base e$ and the common logarithm $base 10$.

Highlight: A logarithm is positive when both the base and the argument are greater than 1 or when both are between 0 and 1.

The page concludes with important relationships between logarithms and exponents, such as a^$log_a b$ = b and log_a $a^x$ = x.

Logarithm Theorems and Change of Base Formula

This page delves into the important theorems of logarithms and introduces the change of base formula. These properties are crucial for simplifying and solving logarithmic expressions and equations.

Highlight: Key logarithm properties include:

1. log_a $b·c$ = log_a b + log_a c
2. log_a $b/c$ = log_a b - log_a c
3. log_a $b^m$ = m · log_a b

The change of base formula is presented as:

Formula: log_a b = $log_c b$ / $log_c a$

This formula allows for the conversion between logarithms of different bases, which is particularly useful when working with calculators or when simplifying complex logarithmic expressions.

Example: log_2 8 can be calculated using the natural logarithm as ln 8 / ln 2.

These properties and the change of base formula are essential tools for manipulating and solving logarithmic functions and equations.

Logarithmic Equations

This page focuses on logarithmic equations, which are equations where the unknown variable appears as the argument of a logarithm. The page begins by introducing the elementary logarithmic equation:

Definition: An elementary logarithmic equation has the form log_a x = b, with the solution x = a^b, where x > 0.

The page then outlines three general types of logarithmic equations and their solving methods:

1. log_a f$x$ = k
2. f$x$ = log_a g$x$
3. a_1 log_a x + a_2 log_a x + a_3 = 0

Example: To solve log_2 x = 3, we get x = 2^3 = 8.

The solving process often involves substitution and solving resulting quadratic equations. The page emphasizes the importance of checking solutions against the domain restrictions of logarithms.

Highlight: Always remember the condition x > 0 when solving logarithmic equations, as logarithms are only defined for positive arguments.

Logarithmic Functions

This page explores logarithmic functions, which are the inverse of exponential functions. The general form of a logarithmic function is y = log_a x.

The graph of a logarithmic function depends on the base a:

• For a > 1, the function is increasing.
• For 0 < a < 1, the function is decreasing.

Highlight: The domain of all logarithmic functions is x > 0, and the y-axis $x = 1$ is always an asymptote.

Example: The natural logarithm function y = ln x is an increasing logarithmic function with base e ≈ 2.718.

The page includes graphical representations of logarithmic functions, illustrating their key features such as the y-intercept at $1,0$ and their behavior as x approaches 0 and positive infinity.

Exponential and Logarithmic Inequalities

This final page covers exponential and logarithmic inequalities, which are crucial in solving many real-world problems involving growth and decay.

For exponential inequalities:

• a^$f(x$) > k becomes f$x$ > log_a k for a > 1
• a^$f(x$) < k becomes f$x$ < log_a k for 0 < a < 1

Example: Solve 2^x > 8. This becomes x > log_2 8 = 3.

For logarithmic inequalities:

• log_a f$x$ > k becomes f$x$ > a^k for a > 1
• log_a f$x$ < k becomes 0 < f$x$ < a^k for a > 1

Highlight: Always consider the domain restrictions when solving logarithmic inequalities: f$x$ > 0.

The page also includes compound inequalities and systems of inequalities involving exponential and logarithmic functions.

Vocabulary: A compound inequality involves two or more inequalities combined with "and" or "or" statements.

This comprehensive overview of exponential and logarithmic inequalities completes the guide, providing students with the tools to tackle a wide range of problems in this important area of mathematics.

Exponential Equations and Functions

Exponential equations are a fundamental concept in mathematics, particularly in the study of exponential functions. This page introduces the basic form of exponential equations and their solutions.

An elementary exponential equation takes the form a^x = b, where a > 0, a ≠ 1, and b > 0. Under these conditions, the solution is unique and equal to x = log_a b. The page also outlines three general types of exponential equations and their solving methods.

Definition: An exponential equation is an equation where the variable appears in the exponent.

Example: For the equation 2^x = 8, the solution is x = log_2 8 = 3.

The page concludes with a brief introduction to exponential functions, noting that their graphs depend on the base a.

Highlight: Exponential functions with a base greater than 1 are increasing functions, while those with a base between 0 and 1 are decreasing functions.