Which of the following is not a linear equation ?(A) ax + by + c = 0 (B) 0x + 0y + c = 0 (C) 0x + by + c = 0 (D) ax + 0y + c = 0

answer: b It's not a linear equation, because a linear equation is a verticality equation, but here the coefficients of x and y are zero, and that gives c = 0.Therefore, it is not a linear equation set.