Chapter 17: Activities; The Quadratic Formula - Texas Instruments TI-84 PLUS - Graphing Calculator Manual Book

Chapter 17:
Activities

The Quadratic Formula

: This example uses MathPrint™ mode for real answers and Classic mode for non-real
Note
(complex) results. You can also use the Polynomial Root Finder/Simultaneous Equation Solver
application to solve these types of problems with a quick set-up. This application comes preloaded
on your TI-84 Plus and can be downloaded from education.ti.com.
Use the quadratic formula to solve the quadratic equations 2x
2
2x N 6x + 5 = 0.
Graphing the Functions
Before you begin, look at the graphs of the functions to see the approximate locations of the
solutions.
1. Press o to display the Y= editor.
„ ¡ ¹
2. Press
2
Y1, and then press Í.
„ ¡ ¹
3. Press
2
4. Press q and select
graph of the functions displays.
You can see that the graph of the first
2
function, 2x N 11x + 14 = 0, crosses the
x-axis, so it has a real solution. The graph of
the second function does not cross the
x-axis, so it has a complex solution.
„ Ã
for
11 14
„ Ã
for Y2.
6 5
. The
4:ZDecimal
2
N 11x + 14 = 0 and

Chapter 17: Activities

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