Today’s Date:

9/27/11

3.3 Slope of a Line

Slope

Slope = rise

run

(change in y)

(change in x)

y

x

y

x

run

rise 3slope

4

Zero

Undefined

Slope

Given 2 points: 1 1 2 2( , ) & ( , )x y x y

2 1

2 1

y ym

x x

(slope)

Ex 1) Find the slope of the line with points (–2, 3) & (4, –1)1 1 2 2( , ) ( , )x y x y

1 3 4 2

4 2 6 3m

Slope

The slope of the line Ax + By = C is: A

B

5 2 20

2 5 202 2 2

510

2

x y

y x

y x

A = 5

Ex 2) Find the slope of 5x – 2y= 20

5 5

2 2

Am

B

B = –2 OR Change to slope-intercept formy = mx + b

slope

Find the value of k so that the line has slope m

Ex 3) 6x + ky = 10, m = –2

A = 6 B = k

62

2 6

3

Am

B

kk

k

(k)(k)( )

133

3(3 ) 1

9 3 1

9 2 1

2 8

k

kk k

k k

k

k

2 1

2 1

2 ( 1)3

32 1

33

y ym

x x

k

kk

k

Find the value of k so that the line has slope m

Ex 4) (k, k + 1), (3, 2) , m = 3

(3 – k) (3 – k)

1 1 2 2( , ) ( , )x y x y

4k

don’t forget ( )

Homework

#302 Pg. 116 1 – 23 odd & 39 – 45 odd

For # 1 – 11:

0 #

# 0m m = 0 = Undefined

wayO N

K O