Algebra 2cc Section 2.9
Use a graphing calculator to graph functions, find
max/min values, intercepts, and solve quadratic
equations
Recall: The graph of a quadratic
function y = ax2 + bx + c is a parabola
Use a graphing calculator to graph the parabola, find its
max/min value, and its x intercepts.
y = x2 + x - 6
y = -½ x2 - 3x + 4
Steps to graph a function.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Graph an equation
TI 84
Set the window (domain and range) by using the
keys
Zoom
Zstandard
Y=
Type in the equation using [X,T,θ] for the variable.
Press
Graph
TI Nspire
Use scratchpad: [B Graph]
menu
Graph type
Function
Type equation f(x)=
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Find the maximum/ minimum/ zero of a function’s
graph
TI 84
Graph the function using the Y= key (see
instructions for graphing)
2nd
Trace
max/min/zero
Move the cursor to the left of the max/min/zero
and enter. Move the cursor to the right of the
max/min/zero and enter. Move the cursor close to
the max/min/zero and enter. The max/min/zero
appears at bottom of screen.
TI N-spire
Graph the function (see instructions for graphing)
menu
Analyze graph
max/min/zero
Move the cursor to the left of the max/min/zero
and enter. Move the cursor to the right of the
max/min/zero and enter. Move the cursor close to
the max/min/zero and enter. The max/min/zero
appears at bottom of screen.
Use a graphing calculator to graph the parabola, find its
max/min value, and its x intercepts.
y = 2x2 + 3x + 8
The real solutions to a quadratic equation ax2 + bx + c = 0
can be found using a graphing calculator.
Find all real solutions using a
calculator.
3x2 + 16x + 5 = 0
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Solve a polynomial equation
TI84 (solve graphically)
Graph the equation as a function. (set it
equal to y)
2nd
Trace
Zero/root
Move the cursor to both sides of the x
intercept hitting [enter] on left(lower) and
right(upper) bound. The zero(root/solution)
will appear at bottom of screen.
TI Nspire
Use scratchpad: [A Calculate]
Menu
algebra
Polynomial tools
Find roots of poly
Enter the degree (2 for quadratic). Enter
type of roots (real of complex). Enter the
coefficients of the polynomial equation.
Find the real solutions using a graphing calculator.
-5x = 2x2 - 7
3x2 + 5x = 2
An object is launched at 19.6 meters per second (m/s) from a
58.8-meter tall platform. The equation for the object's height s
at time t seconds after launch is h = –4.9t2 + 19.6t + 58.8, where
h is in meters. When does the object strike the ground? When
does it reach its maximum height? What is the maximum
height?
A rectangle corral is to be built using 70m of fencing. If
the fencing has to enclose all four sides of the corral,
what is the maximum possible area of the corral in
square meters?
• Assignment: worksheet