2.4 Writing Equations of Lines

 

Slope-intercept form: the slope is m, the y intercept b: y= mx+b

 

Point-slope form: given the slope m and a point (x1, y2 ) use this equation: y-y1= m(x-x1)

 

Two points: given 2 points (x1, y1) and (x2, y2) use this formula: m= y2-y1 / x2-x1 to find slope.

 

Example 1

(0, -1) (2,2)

2—1= 3           2-0= 2

Slope (m) = 3/2

 

Finding b:

2= 2(3/2) +b

2= 3+b                         y=3/2x-1

-3  -3

B= -1

 

Another way:

y-2= 3/2(x-2)

y-2= 3/2x-3

 +2          +2

Y= 3/2x-1