posted by Jacob on .
Find the equation of the straight line joining
a)(4, 4) and ( 2, 0)
b)(3, -1), (5, 4)
i also need to know how you went about solving this problem so i can understand.. many thanks
take the generic straight line:
y=mx + b.
Put in the first point: (4,4)
4=4m+b let this be the equation 1)
put in the second point in the generic
Now you have two equations, and two unknowns (m,b). Solve them. In this case subtract the second equation from the first, which yields
4=2m or m=2
This makes b=-4 check that.
A slight variation of bobpursey's method for #2
slope = (4+1)/(5-3) = 5/2
let the equation be y = (5/2)x + b
sub in the point (5,4)
4 = 5/2(5) + b
8 = 25 + 2b
b = -17/2
so y = (5/2)x - 17/2