Introduction (P) Tables (1.2) Rule Use parentheses ( and ) to maintain order of operations with fractions and exponents. Note Use the 2nd ANS key to recall the result of the last operation. Note Use the 2nd ENTRY key to recall the last set of keystrokes. Functions and Models (1.1) Def’n A function describes a relationship between inputs and an output. Def’n A model uses a function to describe a real situation or process. Note Functions can be represented using formulas, tables, or graphs. Formulas (1.1) Def’n A formula describes a function using numbers, letters, and symbols. Def’n When equation notation is used, the output variable is represented by only a letter. Def’n When function notation is used, the output variable makes reference to the input variable(s). Def’n A table describes a function using columns of input and output values. Rule When estimating an output value for an input value halfway between two table values, average the two corresponding output values. Average Rate of Change (1.2) Def’n The average rate of change of a function is the difference in the output variable divided by the difference in the input variable. AROC output input Def’n A limiting value exists whenever output values level off while input values continue to rise. Graphs (1.3) Def’n A graph describes a function using a two-dimensional picture with labels and headings. Def’n A graph is increasing if it rises from left to right, and decreasing if it falls from left to right. Creating Tables in the TI-83 (2.1) Type an equation into Y1 using the Y= key. Select the table features using the 2nd TBLSET key. View the table using the 2nd TABLE key. Def’n The minimum is the lowest output value, and the maximum is the highest output value. Features of TI-83 Tables (2.1) Concavity (1.3) Rule Find limiting values by setting Tbl 1000 . Def’n A graph is concave up if its ends are are bent upward, and concave down if its ends are bent downward. Def’n An inflection point occurs where concavity changes from up to down or from down to up. Rule Find input values, inflection points, minimum values, or maximum values by setting Tbl 0.01. Creating Graphs on the TI-83 (2.2) Type an equation into Y1 using the Y= key. Select the viewing area for the graph using the WINDOW key. View the graph using the GRAPH key. Features of TI-83 Graphs (2.2, 2.4, 2.6) Rule Calculate output values using the 2nd CALC value feature. Slope (3.1) Def’n The slope m of a line is the ratio of the vertical change between any two points on the line to the horizontal change between the same two points: m y rise x run Note The slope formula can be rearranged to solve for y or x as follows: y m x x y m Rule Find limiting values using the TRACE key. Linear Functions (3.2, 3.3) Rule Calculate input values using the 2nd CALC intersect feature. Def’n A linear function is a function with a constant rate of change. Rule Calculate inflection points using the 2nd CALC dy/dx feature Rule A linear function can be written as y mx b , where m is the AROC and b is the initial value. Rule Locate minimum values using the 2nd CALC minimum feature. Rule Locate maximum values using the 2nd CALC maximum feature. Finding Linear Equations (3.2, 3.3) Rule If the slope m and one data point (x , y ) are given, plug the values into the equation y mx b and solve for b. Rule If two data points are given, first calculate the slope m, then plug in and solve for b as above. Modeling Nearly Linear Data (3.4) Exponential Functions (4.1) Rule Model data that are nearly linear using a method called least-squares linear regression. Def’n An exponential function is a function with a constant percentage rate of change. Type the input values into L1 and the output values into L2 using the STAT EDIT feature. Calculate the line of best fit using the STAT CALC LinReg(axb) feature. View the graph of the points and the line using the 2nd STATPLOT key. Rule An exponential function can be written as y a b x , where a is the initial value and b is the growth or decay factor. Rule A factor greater than one indicates growth, while a factor less than one indicates decay. Def’n The growth or decay rate r is given by: r b 1, and the growth or decay factor b is given by: b r 1 . Solving Linear Systems (3.5) Rule Solve linear systems by: (1) writing two equations from words, (2) solving both equations for the same variable, (3) typing the equations into Y1 and Y2, and (4) locating the intersection of the graphs of the equations using the 2nd CALC intersect feature. Unit Conversion for Factors and Rates (4.2) Rule The growth or decay factor for a time period of k units is bk, while a growth or decay rate for a time period of k units cannot be found directly. Rule Exponential growth can be shown using by a doubling time, and exponential decay can be shown using a half-life. Finding Exponential Equations (4.1-4.3) Power Functions (5.2) Rule If the growth or decay factor b and and one data point (x , y ) are given, plug the values into the equation y a b x and solve for a. Def’n A power function is a function with an output that is proportional to a power of the input. Rule If a doubling time or half-life x is given, plug the values into the equation y a b x and solve for b. Rule If two adjacent data points are given, first calculate the factor b y 2 y1 , then plug in and solve for a as above. Exponential Regression (4.4) Rule Model data that are nearly exponential using exponential regression. Rule A power function can be written as y a x b , where a is a constant and b is the power. Rule If the input is multiplied by k, then the output is multiplied by kb. Power (5.2) Rule If b 1, the function is increasing and concave up. If 0 b 1, the function is increasing and concave down. If b 0 , the function is decreasing and concave up. Finding Power Equations (5.2) Rule If the power b and one data point (x , y ) are given, plug the values into the equation y a x b and solve for a. Power Regression (5.3) Rule Model data that are nearly power using power regression. Logistic Functions (5.1) Quadratic Functions (5.5) Def’n A logistic function is a function that modifies exponential growth by limiting the output value. Rule A quadratic function can be written as y ax 2 bx c , where c is the initial value. Rule A logistic function can be written C as y , where C is the 1 a e Rx Rule The graph of a quadratic function is a parabola with either a maximum or minimum value. carrying capacity, C 1a is the initial value, and R is the intrinsic growth rate. Rule A logistic function has an inflection point located where y C 2 . Rule Model data that are nearly quadratic using quadratic regression. Cubic Functions (5.5) Rule A cubic function can be written as y ax 3 bx 2 cx d . Rule The corresponding exponential growth factor is given by: b e R , and the intrinsic growth rate is given by: R ln b . Rule The graph of a cubic function has an inflection point and changes direction twice. Rule Model data that are nearly logistic using logistic regression. Rule Model data that are nearly cubtic using cubic regression. Rational Functions (5.5) Rule A rational function can be written as a ratio of two polynomial functions. Rule A rational function may have a limiting value, vertical asymptotes, both, or neither.