We have already learned about slope and $y$yintercept.
Use the applet below to refresh your memory on slope and $y$yintercept and try to answer the following questions:
The applet above highlights that the $m$m value affects the steepness of the line, or the slope.
We also found that the $b$b value affects the $y$yintercept, or where the line crosses the $y$yaxis.
In the equation $y=mx+b$y=mx+b, the terms $m$m and $b$b are called parameters. A parameter is a placeholder for a value that indicates certain characteristics of a function, such as its slope or $y$yintercept.
A linear equation is said to be in slopeintercept form when it is expressed as
y=m*x+b
where $m$m is the slope and $b$b is the $y$yintercept.
To graph any line you only need two points that are on the line. When we are given an equation in slopeintercept form, we are given one point (the $y$yintercept) and the ability to find a second point (using the slope), so we are all set!
Here is a little more detail on step 2.
For a slope of $4$4, move $1$1 unit across and $4$4 units up.  For a slope of $3$−3, move $1$1 unit across and $3$3 units down.  For a slope of $\frac{1}{2}$12, move $1$1 unit across and $\frac{1}{2}$12 unit up. 
Graph the line with equation $y=2x+4$y=−2x+4.
Think: The slope is $2$−2 and the $y$yintercept is $4$4. How do we put that information on the graph?
Do:


$\text{slope }$slope $=$= $\frac{\text{rise }}{\text{run }}$rise run $=$= $\frac{2}{1}$−21 From the $y$yintercept, move down 2 units and to the right 1 unit. 


Our graphs may not always be in this form so we may need to rearrange the equation to isolate the variable $y$y (that means $y$y is on one side of the equation and everything else is on the other side).
Recall that lines can also be either horizontal or vertical. These types of lines will not look like slopeintercept form. However, they do follow another type of special pattern.
Horizontal lines are the set of all points with a fixed $y$y value. They are parallel to the $x$xaxis and have equations of the form $y=a$y=a, where $a$a is a real number. Recall that horizontal lines have a slope of zero.
Reflect: What happens to the equation $y=mx+b$y=mx+b if you substitute $0$0 for $m$m? How does this relate to the equation of a horizontal line?
Vertical lines are the set of all points with a fixed $x$x value. They are parallel to the $y$yaxis and have equations of the form $x=a$x=a, where $a$a is a real number. Recall that vertical lines have a slope that is undefined.
State the slope and $y$yintercept of the equation, $y=8x1$y=8x−1
Slope  $\editable{}$ 
$y$y  intercept  $\editable{}$ 
State the slope and $y$yintercept of the equation $y=2x$y=−2x
Slope  $\editable{}$ 
$y$y  intercept  $\editable{}$ 
Consider the equation $y=8\frac{2x}{3}$y=−8−2x3.
State the slope of the line.
State the value of the $y$y at the $y$yintercept.
Consider the following graph of a line.
What is the slope of the line shown in the graph?
What is the $y$y value of the $y$yintercept of the line shown in the graph?
What is the equation of the line? Write your answer in slopeintercept form.
Graph the line $y=3x+2$y=3x+2 using its slope and $y$yintercept.
Plot the line $x=4$x=4 on the coordinate plane.
Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear. Describe similarities and differences between linear and nonlinear functions from tables, graphs, verbal descriptions, and equations.