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 3) b = 3 and m = 4

y = -¼x – 7 y = x – 14 y = 4x + 3

If you are given an ordered pair, you know x and y.

4) m = ⅔ and (0, -10) 5) m = ⅜ and (-16, 7) 6) m = -1 and (4, -2)

y = ⅔x – 10 y = ⅜x + 13 y = -x + 2

Standard Form: 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 9) y = 3x + 9

7x + y = 2 x + 2y = 22 3x – y = -9

Write an equation in standard form.

10) m = 5 and b = -16 11) m = -⅞ and (4, 0) 12) m = 1 and (-3, -5)

5x – y = 16 7x + 8y = 28 x – y = 2

Activity: 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) (-2, -10) and (-5, -13)

y = 7/3x + 5 y = x – 8

3) (4, -5) and (2, -4) 4) (5, -12) and (2, 0)

y = -½x – 3 y = -4x + 8

Write an equation in standard form.

5) (-4, 8) and (2, -7) 6) (9, 1) and (-3, -1)

5x + 2y = -4 x – 6y = 3

7) (-1, 8) and (2, -13) 8) (11, 3) and (22, 6)

7x + y = 1 3x – 11y = 0

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 6) 3x – 6y = -18

y = ⅛x + 2 y = 4x + 1 x – 2y = 14

perpendicular neither 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 / Given / Use / Given / Use
m = 7 / m = 7 / m = -½ / m = 2 / m = 7/4 / m = -4/7
X / b = 15 / X / b = -26 / X / b = 41

Write an equation in Slope-Intercept Form.

10) x-int: 12 and y-int: -7 11) x-int: -10 and y-int: 3

y = 7/12x – 7 y = 3/10x + 3

Activity: 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