Answers to warm-up A: (-10, 6) B: (-4, -2) C: (0, -5) D: (3, 0) E: (7, 3)

Algebra 3 Lesson 1.1 Objectives: SSBAT define slope. SSBAT calculate slope given 2 points. SSBAT determine the slope of a line from the graph. SSBAT determine if a line increases/decreases by analyzing the slope. Standards: M11.A and M11.D.3.2.3

Slope of a Line  Denoted as m  Measures how steep the line is - the greater the slope the steeper the line  Rate of Change  Ratio of Vertical Change over Horizontal Change

Positive Slope The line will be going UPHILL from left to right. Negative Slope The line will be going DOWNHILL from left to right.

Finding Slope of a Line from the graph m =

Examples: Find the slope of the given line. 1.

2. Down 2, Right 1 m = m = -2

3. Undefined  The slope of a vertical line is always undefined

(x 1, y 1 ) and (x 2, y 2 ) are points on a line Finding Slope given 2 points on the line.  Reduce the fraction in the end if you can

1.Find the slope of the line containing the points (-2,0) and (3,1)  Does the line go uphill or downhill from left to right? The line will go UPHILL because the slope is positive. m =

2. Find the slope of the line containing the points (0,4) and (1,-1).  Does the line go uphill or downhill from left to right? The line will go Downhill because the slope is negative.

3. Find the slope of the line containing the points (- 1,2) and (2,2) Is the line a Horizontal or Vertical Line?  Horizontal because the slope is 0

4. Find the slope of the line containing the points (-3,4) and (-3,-5) Is the line a Horizontal or Vertical Line?  Vertical because the slope is Undefined.

Give an example of two points that would create a line to be undefined.  Recall a line with an undefined slope means 0 is in the denominator

On Your Own 1.Find the slope of the line through the points (7, 2) and (-3, 5) 2.Does the line that goes through the points above increase or decrease? Decrease – the slope is negative

Homework Worksheet 1.1