Question

Which one of the following is not a quadratic equation?
(A) (x + 2)2 = 2(x + 3) (B) x2 + 3x = (–1) (1 – 3x)2
(C) (x + 2) (x – 1) = x2 – 2x – 3 (D) x3 – x2 + 2x + 1 = (x + 1)3

Answer 1

(c) is not a quadratic equation as

(x+2)(x-1) = x2 - 2x - 3
or, x2 -x - 1 = x2 - 2x - 3
or, 2x - 3 = -x - 1

As degree of polynomial is less than 2, it is not a quadratic equation