graphing linear equations
DESCRIPTION
Graphing Linear Equations. In Slope-Intercept Form. We have already seen that linear equations have two variables and when we plot all the (x,y) pairs that make the equation true we get a line. - PowerPoint PPT PresentationTRANSCRIPT
Graphing Linear Equations
In Slope-Intercept Form
We have already seen that linear equations have two variables and when we plot all the (x,y) pairs that make the equation true we get a line.
In this section, instead of making a table, evaluating y for each x, plotting the points and making a line, we will use The Slope-Intercept Form of the equation to graph the line.
y 2x 1
y x 4
y 32
x 2
These equations are all in Slope-Intercept Form:
The formula for Slope-Intercept Form is:
y mx b;• ‘b’ is the y-intercept.
• ‘m’ is the slope.
On the next three slides we will graph the three equations:
y 2x 1, y x 4, y 3
2x 2
using their y-intercepts and slopes.
y 2x 1
up 2
right 1 up 2
right 1
right 1down 1
right 1
y x 4
down 1
right 2
up 3
y 3
2x 2
right 2
up 3
Sometimes we must solve the equation for y before we can graph it.
2x y 3
y 2x 3
x2 x2
1) Plot the y-intercept as a point on the y-axis. The constant, b = 3, so the y-intercept = 3.
2) Plot more points by counting the slope up the numerator (down if negative) and right the denominator. The coefficient, m = -2, so the slope = -2/1.
right 1down 2
right 1
down 2
y 2x 3
Let’s Practice
35
3 xy xy 3
1027 yx 124 yx
HW
• pg. 298 #12 to 26 even