Objective - To find the x-intercepts and to
solve quadratic equations by graphing.
2
Graph y  x  2x  8
Vertex
(1,9)
y
x y
-3
-2
-1
0
1
2
3
--3  2-3  8  -7
2
--2  2-2  8  0 x-intercepts
2
--1  2-1  8  5
2
-0  20  8  8
x  -2
2
-1  21  8  9
2
-2  22  8  8
2
-3  23  8  5
2
x4
x=1
x
Find the x-intercepts of the equation below.
1 2
y  x  4x  6
2
y
Axis
b  4 
4

x
2a 20.5
Vertex
4,y
1 2
y  4  44  6
2
y  8 16  6
y  2 4,2
x
Find the x-intercepts of the equation below.
1 2
y  x  4x  6
2
y
x-intercepts (set y = 0)
1 2
0  x  4x  6
2
x  2solve
or x yet!
6
Can’t
solved by graphing
x2
x y
x-intercepts
solutions
2 2  8  6 0
zeroes
6 18  24  6 0
roots
x6
x
Solve the quadratic equation below by graphing.
2
x  2x  3
3  3
2
x  2x  3  0
Solution: x = -3 or x = 1
y
Find x-intercepts of...
2
y  x  2x  3
x
-3
-2
-1
0
1
2
y
-32  2-3  3  0 x  -3
-22  2-2  3  -3
-12  2-1  3  -4
02  20  3  -3
12  21  3  0
2  22  3  5
2
x 1
x
Write the quadratic equation you would graph
to solve each quadratic equation below.
2
2
3) 3x  2  x
1) 5x  3x  7  0
2
y  5x  3x  7
2
2) x  8x
8x  8x
2
x  8x  0
2
y  x  8x
2
2
x
x
2
x  3x  2  0
2
y  x  3x  2
2
4) 7x  x  6
2
2
7x  7x
2
0  7x  x  6
2
y  7x  x  6