4.6 Slope-Intercept Form

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

Let’s try graphing using a point and slope: Point (2,3) Slope = 2

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 is solve for “y” and we can see a slope and a point!!!

Some more examples… “b” is the y-intercept

So in order to use this form we must solve for “y” + 5X 3y = 5x x -y = -2x

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 = 2/1 b = (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 1 down 1 right 1 down 1 m = -1/1 b = (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 = 3/2 b = (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 1 down 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 = x + 2y = x – 3y = x + 3y = 24 -2x -y = -2x – 3 y = 2x x 2y = -4x + 6 y = -2x x -3y = 5x x 3y = -4x + 24

Now let’s look at each equation and decide what the slope and y-intercept is. 1.y = -3x y = 2x – 5 3. y = -x 4. 2y = 8x x + 3y = 9 6. x – 2y = 16 m = b = (0,6)m = b = (0,-5) m = b = (0,0) m = b = (0,5) m = b = (0,3)m = b = (0,-8) y = 4x + 5 y = mx + b