Writing equations given m and b or m and a point
Slope-Intercept Form:
y = mx + b
To write an equation in Slope-Intercept Form, you must know m and b.
Write an equation in Slope-Intercept Form.
1)
m = -¼ and b = -7
2)
m = 1 and b = -14
y = -¼x – 7
y = x – 14
3)
b = 3 and m = 4
y = 4x + 3
If you are given an ordered pair, you know x and y.
4)
m = ⅔ and (0, -10)
y = ⅔x – 10
Standard Form:
5)
m = ⅜ and (-16, 7)
y = ⅜x + 13
6)
m = -1 and (4, -2)
y = -x + 2
Ax + By = C where A, B, C are integers and A is positive
Transform the equation into standard form.
7)
y = -7x – 2
8)
y = -½x + 11
7x + y = 2
x + 2y = 22
9)
y = 3x + 9
3x – y = -9
Write an equation in standard form.
10)
m = 5 and b = -16
11)
5x – y = 16
12)
m = 1 and (-3, -5)
x–y=2
Activity:
m = -⅞ and (4, 0)
7x + 8y = 28
Wipe Boards
S/I: m = 6 and b = -18
y = 6x – 18
STD: m = 7/2 and b = 12
7x – 2y = -24
S/I: m = -3/5 and (10, -1)
y = -3/5x + 5
STD: m = -½ and (4, 7)
x + 2y = 18
STD: m = 4 and (0, -3)
4x – y = 3
HOMEWORK:
HW sheet
Writing equations given two points
To write an equation in slope-intercept form, you must know m and b. If you have two
points, find m using the formula, then use it with one of the ordered pairs to find b.
Write an equation in slope-intercept form.
1)
(-6, -9) and (0, 5)
2)
y = 7/3x + 5
3)
(4, -5) and (2, -4)
y = -½x – 3
(-2, -10) and (-5, -13)
y=x–8
4)
(5, -12) and (2, 0)
y = -4x + 8
Write an equation in standard form.
5)
(-4, 8) and (2, -7)
5x + 2y = -4
6)
(9, 1) and (-3, -1)
x – 6y = 3
7)
8)
(11, 3) and (22, 6)
3x – 11y = 0
(-1, 8) and (2, -13)
7x + y = 1
Activity:
Wipe Boards
S/I: (4, 15) and (3, 11)
y = 4x – 1
STD: (6, 22) and (-12, -20)
7x – 3y = -24
S/I: (4, -1) and (8, -7)
y = -3/2x + 5
STD: (-7, 3) and (-2, 2)
x + 5y = 8
STD: (3, 0) and (0, -6)
2x – y = 6
HOMEWORK:
HW sheet
6-6 Writing equations given a variety of information
2 lines are parallel if they have the same slope. The symbol that represents parallel is ║
2 lines are perpendicular if they have negative reciprocal slopes. The symbol that
represents perpendicular is 
1)
What is the slope of the line parallel to a line whose slope is 6? 6
2)
What is the slope of a line perpendicular to a line whose slope is –¾? 4/3
3)
If one line has a slope of 3 and another line has a slope of ⅓ are they parallel,
perpendicular or neither? neither
Determine if the lines are parallel, perpendicular or neither.
4)
y = -8x – 10
5)
4y = x + 12
y = ⅛x + 2
y = 4x + 1
perpendicular
neither
6)
3x – 6y = -18
x – 2y = 14
parallel
Write an equation in Slope-Intercept Form. State what you are given and what you will
use.
7)
║ to y = 7x + 2
8)
 to x + 2y = -10
9)
 to 4y = 7x - 8
through (-1, 8)
through (3, -20)
through (28, -8)
y = 7x + 15
y = 2x – 26
y = -7/4x + 41
Given
Use
m=7
m=7
X
b = 15
Given
m = -½
X
Write an equation in Slope-Intercept Form.
10)
x-int: 12 and y-int: -7
11)
y = 7/12x – 7
Activity:
Use
m=2
Given
Use
m = 7/4
m = -4/7
b = -26
X
x-int: -10 and y-int: 3
y = 3/10x + 3
Wipe Boards
 to y = 2/7x + 1 through (-2, 14)
y = -7/2x + 7
║ to x – 3y = 9 through (18, -2)
y = ⅓x – 8
║ to 5y = -3x + 5 through (15, -4)
y = -3/5x + 5
x-int: -5 and y-int: -2
y = -2/5x – 2
HOMEWORK:
HW sheet
b = 41