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

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)=

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 lines 2x-ay+1=0, 3x-by+1=0, 4x-cy+1=0 are concurrent, then a, b, c are in

If the lines ax+12y+1=0, bx+13y+1=0 and cx+14y+1=0 are concurrent, then a,b,c are in:

If the lines ax + 2y + 1 = 0, bx + 3y + 1 = 0, cx + 4y + 1 = 0 are concurrent, then a, b, c are in

If the lines ax + by + c = 0, bx + cy + a = 0 and cx + ay + b = 0 be concurrent, then:

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