4.1 Graphing Equations in Slope-Intercept Form

Investigation

• In groups, you will investigate slope and y-intercepts using graphing calculators

Discussion

1) What happens to m when the graph is less steep than y = x?

2) Does changing the value of m cause the line to curve or become something other than a straight line?

3) Does changing the m change the y-intercept?

4) How does addition or subtraction change b?

5) Does changing the b affect the steepness of the graph?

6) Does changing the b determine whether the graph is positive or negative?

7) Does changing the b cause the graph to become curved or another figure?

Slope-Intercept Form

y = mx + b

What is the m?

What is the b?

Write the equation in slope intercept form and then graph.

a)Slope: ¼, y-intercept: -1

b)Slope: 4, y-intercept: 3

Graph 4y + 5x = 8

Graph 3x + 2y = 6

Graph y = -7

Which of the following is an equation in slope-intercept form for the line shown in the graph?

A.

B.

C.

D.

• The ideal maximum heart rate for a 25-year-old exercising to burn fat is 117 beats per minute. For every 5 years older than 25, that ideal rate drops 3 beats per minute.

• A. Write a linear equation to find the ideal maximum heart rate for anyone over 25 who is exercising to burn fat.

B. Graph the equation.

C. Find the ideal maximum heart rate for a 55-year-old person exercising to burn fat.