Writing equations from graphs

Slope-intercept form (Algebra Introduction)

What do we know from this graph?

• slope m = -4

• y-intercept b = (0,1)

• slope intercept form

• y = -4x + 1

What do we know about this graph?

slope m = 0

y-intercept b = (0,-1)

slope-intercept

y=0x - 1

y = -1

What do we know from this graph?

What do we know about this graph?

Multiple Choice

Which equation is the slope-intercept form of the graph?

• $$y=-2x+3$$

• $$y=-\frac{2}{5}x-3$$

• $$y=\frac{2}{5}x+3$$

• $$y=-\frac{2}{5}x+3$$

Explanation Slide...

Start by identifying where the graphed line crosses the y-axis - this is the "b" or "begin" value of the graph, b = 1. Next, determine the slope or "move" value between 2 points. Here the move value is up 2 left 1, making the slope value -2/1 or m = -2. The equation is y = -2x +1.

Multiple Choice

Write an equation that represents the graphed line.

• y = 2x + 1

• y = -2x + 1

• y = -2x

• y = 2x - 1

Multiple Choice

Write an equation that represents the graphed line.

• y = x

• y = -x + 2

• y = -2x - 2

• y = x - 2

Multiple Choice

• $$y\ =\ \frac{4}{3}x-4$$  

• $$y\ =\ \frac{4}{3}x+4$$  

• $$y\ =\ \frac{4}{3}x+3$$  

• $$y\ =\ -\frac{4}{3}x\ -\ 3$$  

Multiple Choice

Which of the following equations may be used to generate the graph shown?

• $$y\ =\ \frac{7}{2}x\ -\ 2$$  

• $$y\ =\ \frac{7}{2}x\ +\ 2$$  

• $$y\ =\ \frac{1}{5}x\ -\ 2$$  

• $$y\ =\ -\frac{7}{2}x\ -\ 2$$