Question 785322
x1	y1	x2	y2									
1      	-2    	-1    	-1    									
												
The general equation of the line when co-ordinates of two points are given is												
												
{{{(y-	y1)/(	y1-y2) = (x-x1)/(x1-x2)}}}										
												
{{{(y-	-2    	)/(	-2    	-	-1    	)=(x-	1      	)/(	1    	-	-1    	)}}}
												
												
{{{(y	2      	)/(	-1      	x	-1      	) /(	2      	)}}}				
												
{{{ 	2      	(y+	2      	) =	-1      	(x-	1      	)}}}				
												
2      	y+	4      	=	-1      	x+	-1      						
												
2      	y=	-1      	x	-5      								
/	2      											
y=	-  1/ 2	x	-5/ 2