11. (0,0), (-4,5). The slope of the line through these points is (5-0)/(-4-0) = -5/4. You can use any of the two points given so we will use the first. y-0=-5/4(x-0) which can also be written as y=-5x/4.
12. (-1,7), (3,-1). The slope of the line through these points is
(-1-7)/(3--1) = -8/4 = -2. You can use any of the two points given so we will
use the first. y-7=-5/4(x--1) which can also be written as y-7=-2(x+1).
13. (-1,-9), (5,18). The slope of the line through these points is
(18--9)/(5--1) = 27/6 = 9/2. You can use any of the two points given so we will
use the first. y--9=9/2(x--1) which can also be written as y+9=9/2(x+1).
