Chapter 17: Activities
296
Chapter 17:
Activities
The Quadratic Formula
Note
: This example uses MathPrint™ mode for real answers and Classic mode for non-real
(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
.
Use the quadratic formula to solve the quadratic equations 2x
2
N
11x + 14 = 0 and
2x
2
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.
2. Press
2
„ ¡ ¹
11
„ Ã
14
for
Y1, and then press
Í
.
3. Press
2
„ ¡ ¹
6
„ Ã
5
for Y2.
4. Press
q
and select
4:ZDecimal
. The
graph of the functions displays.
You can see that the graph of the first
function, 2x
2
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.
