If a12+b12−c12=0, then the value of (a+b−c2) is ____.
Unique point is obtained for the pair of equations a1x + b1y + c1 = 0 and a2x +b2y + c2 = 0 if __________ .
The condition for a1x+b1y+c1=0 and a2x+b2y+c2=0 to be consistent and have a unique solution is