Slope intercept form

Slope intercept form

Lesson 4.5 p. 225-

Recall: Proportional relationships

• straight lines that go thru (0,0)

• y=kx where k=constant of proportionality or unit rate

Multiple Select

Which equations are proportional?

•  $y=-4x$  

•  $y=3x+7$  

•  $y=0.5x$  

•  $y=.75x\ -12$  

Multiple Choice

Select the unit rate

• 12 miles per gallon

• 24 miles per 2 gallons

• 120 miles per 10 gallons

Nonproportional linear relationships can be written in the form

 $y=mx+b$   

This is called slope-intercept form.

• m is the slope and b is the y-intercept

• The y-intercept of a line is the y-coordinate of the point where the lines crosses the y-axis

Ex 1 p. 226

 $y=\frac{2}{3}x-4$  

• You can rewrite subtracting 4 as +-4?

•  $y=\frac{2}{3}x\ +-4$  

• m= ?   b=?

Multiple Choice

In

 $y=\frac{2}{3}x\ +-4\ what\ is\ the\ m\ and\ the\ b?$  

• m=2   b =4

• m=2/3   b= 4

• m=2/3, b=-4

Fill in the Blank

Check p. 227 top

 $y=-\frac{2}{5}x\ -1^{ }$  what is the m and b?

Ex. 2 p. 227 Write the equation of a line in slope-intercept form with a slope of -3 and y-intercept of -4.

•  $y=mx+b$  

•  $y=-3x+\left(-4\right)$  

•  $y=-3x-4$  

Open Ended

What is slope-intercept form?

Check p. 227 bottom : Write the equation of a line in slope-intercept form with a slope of 5 and a y-intercept of -7

•  $y=mx+b$  

•  $y=5x+\left(-7\right)$  

•  $y=5x-7$  

Multiple Choice

p. 235 #1 Identify the slope and y-intercept of

 $y=\frac{1}{2}x-5$  

• m=x; b=5

• m=0.5; b=5

• m=0.5 or 1/2; b=-5

Multiple Select

p. 235 #2 Identify the slope and y-intercept of

 $y=3x-1$  

• m=-1

• m=3

• b=3

• b=-1

• b=1

Multiple Choice

p. 235 #3

• $y=\frac{-1}{3}x-4$

• $y=-\frac{1}{3}x\ +4$

• $y=4x-\frac{1}{3}$

Multiple Select

p.235 #4

• $y=\frac{3}{2}x-3$

• $y=-3x+\frac{3}{2}$

Open Ended

p. 235 #5

Open Ended

p. 235 #6