Sections
What is a “quadratic” function?
Graph of a quadratic function…
What must you be able to do with quadratic functions right now? 1) Graph a quadratic function (either in standard or vertex form) 2) Convert a quadratic function to either standard or vertex form given the other form 3) Write a quadratic function (in either form) given information
Procedure for graphing quadratic functions (in standard form)…
5) Select two other values of x and solve for their y- values; plot these points (if possible, choose 0 as one of your values!) 6) Find the “reflection (corresponding) points” of those two points and plot these points as well 7) Draw your graph through your points…done! No parab-lem!
Let’s graph some parabolas!
There is another form…
Procedure for graphing quadratic functions (in vertex form)… use same procedure as before (start at step #4)
Let’s graph some more parabolas!
Family Reunion!
Let’s try some…
Writing Quadratic Functions…
When given a table of values: - press STAT, then choose option 1 EDIT - enter the data (each row is a column on the calculator) - after you finished entering the data, press STAT, move the cursor to CALC, then choose option 5 QUADREG (Quadratic Regression Line) - write the quadratic function using the information given
Let’s try some… Given the following table of values, determine the quadratic function associated with them: A) B)
Translations… one can use vertex form to write “translation equations” of quadratic functions translation- when a graph is moved around the coordinate plane (does not affect either size of shape of graph) - three types of translations: horizontal, vertical, and diagonal translations start from “parent functions” (the function representing the graph that is to be moved)
Translations… Rules for writing translation equations: - if you move left, the sign inside the parentheses is positive - if you move right, the sign inside the parentheses is negative - if you move up, the sign at the end of the function is positive - if you move down, the sign at the end of the function is negative
Let’s try some…