Question

check whether the following are quadratic equations....

* (X-2) (X+1) =(X-1) (X+3)

Answer 1

$(x - 2)(x + 1) = (x - 1)(x + 3) \\ {x}^{2} + x - 2x - 2 = {x}^{2} + 3x - x - 3 \\ - x - 2x- 2 + 3 = 0 \\ = 3x + 1$
therefore it's not a quadratic equation