create an equation of each of the following lines ?

Question

a) The slope is -2 and the point (2, -3) is on the line.
b) The line passes through the points (-3, 3) and (6, 9).

Answer 1

a.  The slope is -2 and the point (2, -3) is on the line. 

We use the point slope method where 

 

y - y1 = slope * (x - x1)

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

y +3 = -2x +4

y = -2x + 1

 

b. The line passes through the points (-3, 3) and (6, 9).

 

We use the point slope method but need the slope first.

 

Slope = (y2-y1)/(x2-x1) = (9-3)/(6-(-3)) = 6/9 = 2/3

 

y - y1 = slope * (x - x1)

 

y - 3= 2/3 * (x - (-3)) = 2/3x +3 + 3*2/3 = 2/3x +5

 

y = 2/3x +5