Chapter 4

4.6 Slope Intercept Form

Objectives Write a linear equation in slope-intercept form. Graph a line using slope-intercept form.

Slope intercept form You have seen that you can graph a line if you

know two points on the line. Another way is to use the slope of the line and the point that contains the y-intercept.

This is y= mx+b also known as the slope intercept form

Example#1 Graph the line given the slope and y-

intercept.Slope = -2/5 and y = 4

Example #2 Graph the line given the slope and y-

intercept. slope = 2, y-intercept = –3

Student guided practice Do problems 1-4 in your book pg.272

Sloe-intercept form you know the slope of a line and the y-

intercept, you can write an equation that describes the line.

Example #3 If a line has a slope of 2 and the y-intercept is

3.Write the slope intercept form of the line.

Example#4 Write the equation that describes the

line in slope-intercept form. slope =1/4 ; y-intercept = 4

Example Write the equation that describes the

line in slope-intercept form. slope = –9; y-intercept = 5/4

Student guided practice Do problems 6 and 7 in your book page 272

Example Write the equation that describes the

line in slope-intercept form.

Example Write the equation that describes the

line in slope-intercept form. slope = 2; (3, 4) is on the line.

Example Write the equation in slope-intercept

form. Then graph the line described by the equation.

A)y = 3x – 1 B) 2y + 3x = 6

Example Write the equation in slope-intercept

form. Then graph the line described by the equation.

Y=-4

Student guided practice Do problems 10 to 12 in your book page 272

Application A closet organizer charges a $100 initial

consultation fee plus $30 per hour. The cost as a function of the number of hours worked is graphed below.

Application a. Write an equation that represents the

cost as a function of the number of hours.

Solution

Cost is $30for each

hour plus $100

y = 30 •x + 100

An equation is y = 30x + 100.

Application A caterer charges a $200 fee plus $18

per person served. The cost as a function of the number of guests is shown in the graph.

. Write an equation that represents the cost as a function of the number of guests.

Homework Do problems 14-20 in your book page 272

Closure Today we learned about the slope intercept

form Next class we are going to learned about

point-slope form.