Question 71129
SLOPE=(Y2-Y1)/(X2-X1)
(4-3)/(2-1)=1/1=1
NOW SUBSTITUTE ONE SET OF (X,Y) POINTS AND SOLVE FOR THE Y INTERCEPT. THUS
3=1*1+b
3=1+b
b=3-1
b=2 THUS THE EQUATION OF THIS LINE IS 
Y=X+2
{{{ graph( 200, 200, -6, 5, -10, 10, y = x +2) }}} (graph 200x200 pixels, x from -6 to 5, y from -10 to 10, y = x +2).