뒤로Precalculus Study Guide: Key Objectives Through Chapter 4.3
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Exponents and Quadratic Equations
Simplifying Exponential Expressions Involving Integer Exponents
Exponential expressions with integer exponents can be simplified using the laws of exponents. These rules help in rewriting expressions in a more manageable form.
Product Rule:
Quotient Rule:
Power Rule:
Zero Exponent: (for )
Negative Exponent:
Example: Simplify
Solving Quadratic Equations Using the Quadratic Formula
Quadratic equations are equations of the form . The quadratic formula provides a method for finding their solutions.
Quadratic Formula:
The expression under the square root, , is called the discriminant.
If the discriminant is positive, there are two real solutions; if zero, one real solution; if negative, two complex solutions.
Example: Solve using the quadratic formula.
Linear Equations and Graphs
Finding the Equation of a Line Using the Slope-Intercept Form
The slope-intercept form of a line is , where is the slope and is the y-intercept.
Given a point and slope , the equation is (point-slope form), which can be rearranged to slope-intercept form.
Example: Find the equation of a line with slope $2(1, 3)y - 3 = 2(x - 1) \implies y = 2x + 1$
Determining the Slope of a Line
The slope of a line measures its steepness and is calculated as the ratio of the change in to the change in between two points.
Slope Formula:
Example: For points and ,
Finding the Equations of Parallel and Perpendicular Lines
Parallel lines have the same slope:
Perpendicular lines have slopes that are negative reciprocals:
Example: A line perpendicular to has slope
Functions and Their Properties
Using Function Notation; Evaluating Functions
A function assigns each input to exactly one output . Function notation is used to express this relationship.
To evaluate, substitute the input value into the function.
Example: If , then
Determining the Domain of a Function Given the Equation
The domain of a function is the set of all input values for which the function is defined.
For rational functions, exclude values that make the denominator zero.
For even roots, exclude values that make the radicand negative.
Example: The domain of is all real numbers except .
Determining Whether a Function Is Even, Odd, or Neither
Functions can be classified based on their symmetry:
Even function: (symmetric about the y-axis)
Odd function: (symmetric about the origin)
Example: is even; is odd.
Determining Information about a Function from a Graph
Graphs can reveal properties such as intercepts, intervals of increase/decrease, and symmetry.
Identify - and -intercepts.
Check for symmetry and behavior at endpoints.
Analyzing Piecewise-Defined Functions
Piecewise functions are defined by different expressions over different intervals of the domain.
Evaluate by determining which interval the input belongs to.
Example:
Using Combinations of Transformations to Graph Functions
Functions can be transformed by shifting, reflecting, stretching, or compressing their graphs.
Vertical shift:
Horizontal shift:
Reflection: (over x-axis), (over y-axis)
Vertical stretch/compression:
Evaluating a Combined Function
Combined functions involve operations such as addition, subtraction, multiplication, or division of two functions.
,
Finding the Intersection of Intervals
The intersection of intervals is the set of numbers common to both intervals.
For example,
Forming and Evaluating Composite Functions
The composite function is defined as .
Evaluate first, then substitute into .
Example: If and , then
Determining the Domain of Composite Functions
The domain of consists of all in the domain of such that is in the domain of .
Understanding the Definition of a One-to-One Function
A function is one-to-one if each output is paired with exactly one input.
No horizontal line intersects the graph more than once.
Determining Whether a Function Is One-to-One Using the Horizontal Line Test
If every horizontal line crosses the graph at most once, the function is one-to-one.
Understanding and Verifying Inverse Functions
The inverse function reverses the effect of .
and
Sketching the Graphs of Inverse Functions
The graph of is the reflection of the graph of across the line .
Finding the Inverse of a One-to-One Function
To find the inverse, solve for and interchange and .
Example: , so
Quadratic and Polynomial Functions
Determining the Equation of a Quadratic Function Given Its Graph
A quadratic function has the form , where is the vertex.
Use the vertex and another point to solve for .
Maximizing Projectile Motion Functions
Projectile motion is modeled by (in feet, with in seconds).
The maximum height occurs at for .
Determining the Real Zeros of Polynomial Functions and Their Multiplicities
The real zeros of a polynomial are the -values where the function equals zero. The multiplicity of a zero is the number of times it occurs as a factor.
If a zero has even multiplicity, the graph touches the -axis and turns around.
If a zero has odd multiplicity, the graph crosses the -axis.
Example: has a zero at (multiplicity 2) and (multiplicity 1).