FCP 10
6.4 Slope-Intercept Form of a Linear Function
Complete the table of values and draw the graph for the equation:
x
y
-2
0
2
3
The y-intercept is:
For the equation,
a) Slope = ___________
b) y-intercept=_______
note: Where is the x-intercept in the equation?
For each of the following, determine the slope and the y-intercept
y
2
x 4
3
y
Slope Intercept Form:
2x
1
3
y
3
x
4
Example 1
The graph of a linear function has slope
this function.
3
and y-intercept of -4. Write an equation for
5
How can you use the slope-intercept form to graph a line from an equation?
Start with the _______________________________________
Use the __________________ to find other coordinates on the line
Example 2
a) y
1
x 3
2
b) y
m=
m=
b=
b=
3
x 2
4
Finding the Equation from a graph:
I should
Example 3
Write an equation for the following linear functions, and then verify them.
Did you know?
The coordinates of a point
on a graph satisfy the
equation of the graph.
If x=1, what y-value
satisfies the equation:
y = 3x + 5
How can you tell the following equations are not in slope intercept form?
3x 2 y 16
Missing Parameters
The equation of a line is y
5x 10 y 9 0
mx 3 . Solve for m if the line contains
the coordinates:
a) (1,2)
b) (-3,-2)
The equation of a line is y
2 x b . Solve for b if the line contains the coordinates:
a) (-3,2)
Put it all together:
Find the equation of a line in slope intercept form that passes through the points (2,6)
and (-1, -4)
Example 4
The student council sponsored a dance (where students actually dance‼‼). A ticket cost
$5 and the cost for the DJ was $300.
a) Write an equation for the profit, P dollars, on the sale of t tickets.
b) Suppose 123 people bought tickets. What was the profit?
c) Suppose the profit was $350. How many people bought tickets?
d) Could the profit be exactly $146? Justify your answer.