1. 

An equation of a line can be written in slopeintercept form
y = mx + b
where m is the slope and b is the yintercept.
The y-intercept is where a line crosses the yaxis.
2.  Suppose
the slope of a line is 5 and the yintercept is 2. How would this you write the
equation of this line in slope-intercept form?
 First
write the slope-intercept form.
y = mx + b
 Now substitute 5 for m and 2 for b.
y = 5x + 2
3. 

y = mx + b
y = 2x + (-4)
y = 2x -4
Where does the line cross
the y-axis?
◦ At the point (0, -4)
◦ The y-intercept is -4.
What is the slope of the line?
◦ The graph also crosses the
x-axis at (2, 0).
◦ We can use the slope
formula to find our slope.
m = -4 – 0 = -4 = 2
0 – 2 -2
We know our slope is 2 and
our y-intercept is -4, what
is the equation of our line?
4. 
Write the equation
of a line with a
slope of -2 and a
y-intercept of 6.


y = mx + b
y = -2x + 6

Write the equation
of a line with a
slope of -4/3 and a
y-intercept of 1.


y = mx + b
y = (-4/3) + 1
5. 
Where does the line cross
the y-axis?
◦
◦


At the point (0, 2)
So the y-intercept b is 2.
The line also passes
through the point (3, 0).
We can use these points
to find the slope of the
line. How? What formula
do we use?
◦
◦
Using the slope formula,
we find that the slope m is
-2/3.
Write the equation of the
line.


y= mx + b
y = (-2/3)x + 2
6. 
Step 1:
 First
find the y-intercept. Substitute the slope m
and the coordinates of the given point (x, y) into
the slope-intercept form, y = mx + b. Then solve
for the y-intercept b.

Step 2:
 Then
write the equation of the line. Substitute
the slope m and the y-intercept b into the slopeintercept form, y = mx + b.
7.  Suppose
we have a slope of -3 and it passes
through the point (1, 2).
◦
We first need to find the y-intercept. We can
do this by substituting our information into
slope-intercept form and solving for b.




y = mx + b
2 = -3(1) + b
2 = -3 + b
5=b
is 5.


y = mx + b
y = -3x + 5
Add 3 to both sides.
Now we know that the y-intercept
8. 
Suppose we have a
line with a slope of
-1 and passes
through the point
(3, 4).







y = mx + b
4 = (-1)3 + b
4 = -3 + b
7=b
y = mx + b
y = (-1)x + 7
y = -x + 7

Suppose we have a
line with a slope of
2 and passes
through the point
(1, 3).






y = mx + b
3 = 2(1) + b
3=2+b
1=b
y = mx + b
y = 2x + 1
9.  Write
an equation f the line that passes
through (-2,5) and (2,1).
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