math
posted by stacy on .
I have trouble finding the solution for this: Find the equation of the line through (2,a) and (4,b).

slope = (ba)/2
using (2,a)
ya = (ba)/2 (x2)
times 2
2y  2a = (ba)(x2)
2y  2a = bx  2b  ax + 2a
ax  bx + 2y = 4a  2b
(ab)x + 2y = 4a  2b
check if point not used lies on it ....
LS= (ab)(4) + 2(b)
= 4a  4b + 2b
= 4a  2b
= RS