Download Parabolas Study Guide

Parabolas Study Guide
Quadratic Equation – standard form
 y = ax2+bx+c
 “a” determines how wide or narrow the parabola will be. The
larger the “a” the more narrow the parabola.
 If “a” is positive, the parabola opens upward and the vertex is a
minimum.
 If “a” is negative, the parabola opens downward and the vertex
is a maximum.
 “b” moves a graph left or right
 “c” moves a graph up or down.
When graphing, first find the axis of symmetry.
x = -b
2a
Then, make a t – chart with the axis of symmetry as the middle point.
y = -2x2 + 8x - 3
Example:
x
0
1
2
3
4
y
-3
3
5
3
-3
The axis of symmetry is x = -8
(2)(-2)
x=2
vertex (2,5)
The roots of the equation are where y = 0.
Example:
Put the equation into standard form x2 - x - 6 = 0.
Enter the left-hand side into Y1
Answer: