1. Drill #23
Determine the value of r so that a line through the points has the given slope:
1. ( r , -1 ) , ( 2 , r ) m = 2
Identify the three forms (Point Slope, Slope-Intercept, and Standard) of each of the following):
2. Slope = -½, passing through (0, -4)
3. Passing through the points (2, 3) and (1, -4)
4. Passing through the points (-4, 7) and (1, 8)

2. Drill #13
Determine the value of r so that a line through the points has the given slope:
1. ( 2 , r ) , ( -1 , 2 ) m = ½ (hint: use the slope formula)
Identify the three forms (Point Slope, Slope-Intercept, and Standard) of each of the following):
2. Slope = -½, passing through (0, -4)
3. Passing through the points (2, 3) and (1, -4)
4. Find the lines parallel and perpendicular to the line 2x + y = 4 passing through (2, 1)
(sketch a graph of #4)

3. 2-4 Writing Linear Equations
Objective: To write an equation of a line in slope intercept form given the slope and one or two points, and to write an equation of a line that is parallel or perpendicular to the graph of a given equation.
Homework: 2-4 Study Guide (#1-8)

4. Slope-Intercept Form*
Definition: An equation in the form of
y = mx + b
where m = slope and b = y- intercept
In order to write an equation in slope-intercept form you need to know the slope (m) and the y- intercept (b)

5. Slope and y-intercept
Find the equation of the line with given slope and y- intercepts:
A. m = 5, b = ¾
B. m = b =
C. m = 0 b = 0

6. Slope and a Point: Two methods
Find the slope-intercept form of a line that has a slope of and passes through (-6, 1).
m = ?
b = ?
Substitute m into the equation y = mx + b.
Substitute (-6, 1) for x and y in the equation.
Solve for b.
Once you know m and b you can put the equation in slope-intercept form.

7. Point Slope Form*: Method2
Definition: An equation in the form of
where
Are the coordinates of a point on the line and m is the slope of the line.
NOTE: For point slope form we need a point and the slope (or two points).

8. Slope and a point
Find the slope-intercept form of the equation of the line with the given line passing through the point:
A. m = 5, b = (0, -3)
B. m = b = (-1, 5)
C. m = ¾ b = (-4, -2)

9. Two Points
Find the equation of the line (in slope-intercept form) passing through the points:
A. (1, 5) and (2, -3)
B. (-2, -5) and (1, 4)

10. Parallel and Perpendicular Lines
Parallel Lines: In a plane, non-vertical lines with the same slope are parallel.
Perpendicular Lines: In a plane, two oblique lines are perpendicular if and only if the product of their slopes is -1.
Writing Equations:
Parallel: Use the Same Slope
Perpendicular: Use the Negative Reciprocal Slope

11. Writing Equations of Lines
1st Determine the slope of the line that we are writing the equation for.
If finding a parallel line use the same slope
If finding a perpendicular line use the negative reciprocal slope
2nd Find a point, any ordered pair (x, y) on the line.
3rd Determine what form you are going to use
If Slope- Intercept, substitute the slope for m and the point (x, y) for x and y into the equation y = mx + b and solve for b
If Point-Slope substitute the point and the slope m into the Point- Slope equation

12. Find the Equation of the Line
That passes through (4, 2) and is
a.) parallel to the line y = 2x – 3
b.) perpendicular to the line y = 2x – 3
Write the equations in all three forms. Graph each line (including the original)

13. Find the Equation of the Line
That passes through (-9, 5) and is
a.) parallel to the line y = -3x + 2
b.) perpendicular to the line y = -3x + 2
Write the equations in all three forms. Graph each line (including the original)