If the lines `x+a y+a=0,\ b x+y+b=0\ a n d\ c x+c y+1=0` are concurrent, then write the value of `2a b c-a b-b c-c adot`

If the lines a x+2y+1=0,b x+3y+1=0a n dc x+4y+1=0 are concurrent, then a ,b ,c are in

If the lines a x+12 y+1=0,\ b x+13 y+1=0 and c x+14 y+1=0 are concurrent, then a , b , c are in

The three lines a x+b y+c=0, b x+c y+a=0 and c x+a y+b=0 are concurrent only when

The lines a x+b y=c, b x+c y=a and c x+a y=b are concurrent, if

If the three lines a x+a^2y+1=0,\ b x+b^2y+1=0\ a n d\ c x+c^2y+1=0 are concurrent, show that at least two of three constants a , b ,\ c are equal.

If the lines x+ay=a=0, bx+y+b=0, cx+cy+1=0 (a,b,c being distinct and !=1 ) are concurrent, then the value of (a/(a-1)+b/(b-1)+c/(c-1)) is

If the straight lines x+y-2=0,2x-y+1=0 and a x+b y-c=0 are concurrent, then the family of lines 2a x+3b y+c=0(a , b , c are nonzero) is concurrent at (a) (2,3) (b) (1/2,1/3) (c) (-1/6,-5/9) (d) (2/3,-7/5)

If the straight lines x+y-2=0,2x-y+1=0 and a x+b y-c=0 are concurrent, then the family of lines 2a x+3b y+c=0(a , b , c are nonzero) is concurrent at (a) (2,3) (b) (1/2,1/3) (c) (-1/6,-5/9) (d) (2/3,-7/5)

If the lines x+ay+a=0, bx+y+b=0, cx+cy+1=0 (a!=b!=c!=1) are concurrent then value of a/(a-1)+b/(b-1)+c/(c-1)=