2.3 Slope2.3 Slope

Finding slope and rate of changeFinding slope and rate of change

Parallel and Perpendicular linesParallel and Perpendicular lines

Slope

Slope is the change in y over the change in x.

Meaning Rise over Run

It is the tilt of the line

Slope = Change in yChange in x

Equation to find slope

Given two points (x1, y1), (x2, y2)

(4, -2), (- 6, 1)

Slope = y1 – y2 = (-2) – (1) = -3

x1 – x2 (4) – (- 6)10

Try the points ( - 3, 8) and (2, -4)

What is the slope?

Slopes can be grouped into classes

Positive Negative

Zero slope Undefined slope

Another name for Slope is Rate of change

Between 8:00 am and 11:00 am the temperature went from 58º to 72º.

Find the rate of change.

The points are (8, 58) and (11, 72)

Another name for Slope is Rate of change

Between 8:00 am and 11:00 am the temperature went from 58º to 72º.

Find the rate of change.The points are (8, 58) and (11, 72)Rate of change = 58 – 72 = -14 14

8 – 11 - 3 3About 4.7 degrees per hour.

Lines with the same slope are called?

Lines with the same slope are called?

Parallel. For example y = 2x + 1

y = 2x – 5

The slopes are both 2, it does not matter about

the y intercept

Perpendicular Lines

Perpendicular lines have opposite reciprocal slope.

If the slope is 2/5,

then its opposite reciprocal would be -5/2

y = ¼x + 4 and y = - 4x + 12Are Perpendicular lines

How to use slope to graph

If you are given a slope ⅜ and a point (1, 2)Find the next point by add 3 to 2 ( the y)

add 8 to 1 ( the x)New point on the line is ( 9, 5).

Slope is similar to giving directions; go 2 blocks north and turn right for 8 blocks.

If a line is not Parallel or Perpendicular then it is Oblique

Oblique means

http://www.merriam-webster.com/dictionary/oblique

.

Homework

Page 72 – 73 #15, 18, 21, 22, 23, 26,

31, 34, 35, 36, 43, 44,45, 46, 47

Homework

Page 72 – 73 # 16,19, 24, 25,

32, 33, 40- 42,48, 50, 58 – 64 even70 – 74 even