tolong bantuin yang nomer 3a,b ya sama cara nya??

3a) misal A (-1, -4) dan B ( 2, 6)
(y-y1)/(y2-y1) = (x-x1)/(x2-x1)
(y- -4)/(6- -4)=(x- -1)/(2- -1)
(y+4)/(6+4) = (x+1)/(2+1)
(y+4)/(10) = (x+1)/(3)
(y+4).3 = (x+1).10
3y +12 = 10x + 10
3y = 10x +10-12
3y = 10x -2
y = (10x -2)/3
y = (10/3)x -2/3
b) A (8, -5) B (1, 3)
(y -y1)/(y2-y1) = (x -x1)/(x2-x1)
(y - -5)/(3- -5)= (x-8)/(1-8)
(y +5)/(3+5)= (x-8)/(-7)
(y +5)/(8) = (x-8)/(-7)
(y +5)(-7) = (x-8).8
-7y -35 = 8x -64
-7y = 8x -64+35
-7y = 8x-29
y = (8x -29)/-7
y = (-8/7)x + 29/7