4.6 slope-intercept form. what are the two ways we know how to graph a linear line so far? 1.) using...
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What are the two ways we know how to graph a
linear line so far?1.) Using a t-chart, and plotting points
2.) Using x and y intercepts
Wouldn’t it be great if we could just look at an equation and figure out it’s slope and a point???!!!
WE CAN!!! YAHHHH!!!!
BY USING SLOPE-INTERCEPT FORM
SLOPE-INTERCEPT FORM
EXAMPLE #1
So all we have to do issolve for “y” and we can see a slope and a point!!!
So in order to use this form we must solve
for “y”+ 5X + 5X
3y = 5x + 9
3 3 3
-4x -4x
-y = -2x + 2
-1 -1 -1
Hand out two sheets of graph
paper to everyone!YOU NEED GRAPH PAPER FOR HW
FOLD UP INTO 6 BOXES ON EACH SIDE
1) Plot the y-intercept as a point on the y-axis. The constant, b = 1, so the y-intercept = 1.
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.
up 2
right 1 up 2
right 1
m = 2/1b = (0, 1)
1) Plot the y-intercept as a point on the y-axis. The constant, b = -4, so the y-intercept = -4.
2) Plot more points by counting the slope up the numerator (down if negative) and right the denominator. The coefficient, m = -1, so the slope = -1/1.
right 1down 1
right 1down 1
m = -1/1b = (0, -4)
1) Plot the y-intercept as a point on the y-axis. The constant, b = -2, so the y-intercept = -2.
2) Plot more points by counting the slope up the numerator (down if negative) and right the denominator. The coefficient, m = 3/2, so the slope = 3/2.
right 2
up 3
right 2
up 3
m = 3/2b = (0, -2)
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
YOU NEED TO SOLVE FOR “Y” FIRST!!
Let’s practice converting an equation to slope-intercept
form.In other words: SOLVE FOR “y”
1. 2x – y = -3 2. 4x + 2y = 6
3. -5x – 3y = 15 4. 4x + 3y = 24
-2x -2x -y = -2x – 3 y = 2x + 3
-4x -4x 2y = -4x + 6 y = -2x + 3
+5x +5x -3y = 5x + 15
-4x -4x 3y = -4x + 24