Quick Graphs Using Slope-Intercept form 4.6 Objective 1 – Graph a linear equation in slope-intercept form

x y Slope-Intercept form of the equation of a line The linear equation y = mx + b is written in slope- intercept form. The slope of the line is m. The y-intercept is b. y = 2x + 3 Slope is 2 y-intercept is 3

a)y = x + 2 b)y = -3x – 4 c)y = 3 d)y = -x e) 2x + y = 6 EXAMPLE 1 Writing equations in slope- intercept form m = 1 m = -3 m = 0 m = -1 m = -2 b = 2 b = -4 b = 3 b = 0 b = 6 Equation Slope y-intercept Rewrite (subtract 2x) -2x y = -2x + 6

EXAMPLE 2 Graphing Using Slope and y-intercept Graph the equation y = 2x + 4 Find the slope and the y-intercept m =2 or b = 4 Plot the y-intercept Use slope to plot second point Draw a line through the two points x y If two lines have the same slope then they are parallel y = 2x

EXAMPLE 3 You try it Graph the equation y = 3x - 1 Find the slope and the y-intercept m =3 or b = -1 Plot the y-intercept Use slope to plot second point Draw a line through the two points x y 3 1

EXAMPLE 4 You try it Graph the equation Find the slope and the y-intercept m = b = 2 Plot the y-intercept Use slope to graph second point Draw a line through the two points x y -2 3