Algebra Period 3 (Friday)

Slope 7-4

You can think of slope of a line as the slope of a ski mountain.

When you are climbing up-- it's positive
When you're sliding down, it's negative.

(Okay, okay-- you must be looking at the mountain from left to right!!)

The steeper the mountain, the higher the slope.
A slope of 5 would be an expert slope because it is much steeper
than a slope of 2 ( an intermediate's slope)

"bunny slopes' for beginners will be the lower numbers--
generally fractional slopes ( like 1/2 or 2/3).

A good benchmark is a slope of 1 or -1. Notice it is a 45 degree angle.

You can also think of slope as rise/run which is read ' rise over run'

Rise is how tall the mountain is ( the y- axis)
Run is how wide the mountain is ( the x value)

A 1000 foot high mountain ( the rise) is very steep-- if it is only 200 feet wide ( the run)
It's slope is 1000/200 = 5/1

Another mountian that is also 1000 feet high is not very steep if it is 2000 feet wide.
It's slope is 1000/2000 = 1/2

You can think of slope as a calculation:

Risexxx= wChange in y values= sDifference in y valuess= swy₂ - y₁
____ ss=s_____________ =s_______________ s= x_____
Run sssssswChange in x value xxx Difference in x value ssw x₂ - x₁

To calculate slope you need 2 coordinates. It doesn't matter which one you start with!! Just be consistent!!. If you start with the y value of one point, make sure you start with the same x!!

Special Slopes:

Horizontal lines in the form of y = k have slopes of ZERO ( they are FLAT)

Vertical lines in the form of x = h have NO SLOPE or UNDEFINED because the denominator is zero.