Monday, 2/8/10

SWBAT…Write and graph eqns in slope-intercept form Agenda

1. WU (10 min)

2. Review hw#5 (25 min)

3. Quiz (15 min)

Warm Up: Q1-2: Write an equation of the line that passes through each pair of points

1. (6, -3), (12, -3) 2. (9, -4), (3, -6)

3. Write an equation of the line that has an x-intercept of -2 and a y-intercept of 4.

HW: Review past notes & re-do in class problems!

Back of agenda practice problems ANSWERS

#5.) y = 6x – 22

#6.) y = -2x + 5

4th period: Monday, 2/8/10

SWBAT…Write and graph eqns w/ parallel (║) and perpendicular(┴) lines Agenda

1. WU (5 min)

2. Review hw#5 (20 min)

3. Brain Pop Video (5 min)

4. Graphing parallel and perpendicular lines – (10 min)

5. Examples (10 min)

Warm Up: Q1-2: Write an equation of the line that passes through each pair of points

1. (6, -3), (12, -3) 2. (9, -4), (3, -6)

3. Write an equation of the line that has an x-intercept of -2 and a y-intercept of 4.

HW#6: Parallel and perpendicular lines

Topic = Writing equations with PARALLEL lines

Graph the below equations on the same coordinate plane:

1.) y = -2/3x + 2 m = ___ 2.) y = -2/3x – 3 m = ___

What can you conclude about parallel lines and their slope?

Ex 1-2 directions: Find the slope of a line parallel to each line given:

Ex 1. y = 3x + 2Answer: m = 3

Ex 2. y = – 4

Answer: m =

x2

1

2

1

Ex 3 directions: Write the equation of a line that is parallel to the line y = ½x – 7 and passes through the point (4, -2).

Step 1: Find the slope:The line parallel to y = ½x – 7 has the same slope, ½. So, m = 1/2

Replace m with ½ and (x, y) with (4, -2) in the slope-intercept form

Step 2: Substitute the values for x and y to find b

y = mx + b-2 = (1/2)(4) + b-2 = 2 + b (Subtract 2 from both sides) -4 = b

Step 3: Write the equation

y = mx + by = ½x + (-4) OR y = ½x – 4

Topic = Writing equations with PERPENDICULAR lines

Graph the below equations on the same coordinate plane:

1.) y = -4x + 2 m = ___ 2.) y = 1/4x – 3 m = ___

What can you conclude about perpendicular lines and their slope?

Ex 4-5 directions: Find the slope of a line perpendicular to each line given:

Ex 4. y = 3x + 2Answer: m = -1/3

Ex 5. y = – 4

Answer: m = -2

x2

1

Ex 6 directions: Write the equation of a line that is perpendicular to the line y = -½x and passes through the point (-2, 0).

Step 1: Find the slope:The line perpendicular to y = -½x has the opposite reciprocal slope, 2. So, m = 2

HW Prob #12

Replace m with 2 and (x, y) with (-2, 0) in the slope-intercept form

Step 2: Substitute the values for x and y to find b

y = mx + b0 = (2)(-2) + b0 = -4 + b (Add 4 to both sides)4 = b

Step 3: Write the equation

y = mx + by = 2x + 4

Write the equation of the line parallel to the line 4x – 5y = 7 that passes through the point (-3, 7).

754 yx

745 xy

57

54 xy

54m

y – y1 = m(x – x1)

)3(7 54 xy

535

512

54 xy

547

54 xy

512

547 xy

37 54 xy

Write the equation of the line perpendicular to the line 3x + 2y = 9 that passes through the point (2, 5).

923 yx

932 xy

29

23 xy

23m

y – y1 = m(x – x1)

25 32 xy

315

34

32 xy

311

32 xy

34

325 xy

32m