|Module 1 - Describing Functions|
|Introduction | Lesson 1 | Lesson 2 | Lesson 3 | Lesson 4 | Self-Test|
|Lesson 1.2: Describing Functions Symbolically|
In this lesson you will define and investigate a function symbolically on the Home screen.
The function you will define is
Defining a Function
From the Home screen,
Notice is a purple key.
1.2.1 What is printed in purple above the key? Click here for the answer.
Evaluating a Function
Now that you have successfully defined the function f(x) = 2x2 5x 3, you can evaluate the function at
Editing the Last Expression in the Edit Line
If you want to evaluate the function at x = 3 just after evaluating f(2), you can edit the current expression in the Edit Line rather than typing in the entire expression "f(3)."
Finding Roots (or Zeros) of Functions
As shown above, one of the
1.2.2 Evaluate the function at other values of x until you find the other root. When you have found the other root, click here for the answer.
If you tried many values until you found the second root, you used a method called
The Algebra Menu's Solve Command
The Algebra menu ( on the Home screen) contains the solve( command, which can help you find the roots directly. To find the roots of f(x) = 2x2 5x 3 by using solve(, follow the steps below.
The roots are x = 3 and .
The Algebra Menu's Factor Command
You may see the relationship between the roots and the factors of f(x) by using the factor( command.
The factors are (x 3) and (2x + 1). Notice that the roots of the factors, (x 3) and (2x + 1), are also the roots of the original function, x = 3 and .
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