Check whether the

Let us solve the above equation,

x (x + 1) + 8 = (x + 2) (x – 2)

x² + x + 8 = (x² + 2x – 2x – 4)

x² + x + 8 = x² – 4

x² + x + 8 - x² + 4 = 0

x + 12 = 0

Since on solving the equation we do not get the second power of x which proves that the following set of equation is not quadratic.