Warm-Up Exercises

1. Graph the equation y = 2x - 3

2. Find the slope of the line that passes through (–5, 6) and (0, 8).

4.5 GRAPH USING SLOPE-INTERCEPT FORMslope-intercept form

y = mx + b m is the slope

*what does slope mean?

b is the y-intercept. *what does y-intercept mean?

rise

run

(line crosses the y-axis)

Steepness of the line

Identify the slope and y-intercept of the line with the given equation.

y = x + 4 m= y = 5x – 3 m = 5 b = 4 b = -3

Now we can use the slope and y-intercept to graph the line.

Step 1: always graph y-intercept (b) first. This is your starting point

Step 2: FROM THAT POINT.. graph the slope of the line(m) using

2

7

rise

run

2

7

Now try these:

Graph each equation.

y = 3x - 5 m= b =

m = b=

y = x + 3 m =b =

y = -2x m =b =

Warm-Up Exercises

1. Identify slope and y-intercept, Then graph y = ½ x - 4

2. Find the slope of the line that passes through (–5, 6) and (-4, 9).

If additional day is needed

A violin teacher charges a one-time sheet-music fee of $20 for adults and no fee for children. The charge per hour is $20 for both children and adults. The cost C for children for n lessons is given by C=20n and for adults by C=20n+20. a. Graph the two equations in the same coordinate plane. b. Based on the graphs, what is the difference in the costs?  

 

Day 2Graphing equations in slope-intercept formWarm-up

1. Solve the equation for “y” 3x – 5y = 10

2. Graph the line of the equation

y = 3x + 2

Today we will graph equations by re-writing them in slope-intercept form first.

Is this equation in slop-intercept form?

3x + y = 2

So to graph a standard equation, re-write it in slope-intercept form (solve for “y”) so you can identify the slope and y-intercept.

The standard equation of a line is__________________________

The slope-intercept equation of a line is______________________

This equation is in Standard Form

 

Write the equation in slope-intercept form. Determine the slope and y-intercept of the line.

1.

2.

 

Write the equation in slope-intercept form. Graph the line.

1.