Check whether the following is quadratic equation or not.
x(x + 1) + 8 = (x + 2) (x - 2)
Here it has been given that,
x(x + 1) + 8 = (x + 2) (x − 2)
Now, solving the above equation further we get,
x2 + x + 8 = x2 - 4
x + 12 = 0
Now as we can see, the above equation clearly does not represent a quadratic equation of the form ax2 + bx + c = 0, because x + 12 = 0 is a linear equation which does not have a x2 term in it.
Hence, the above equation is not a quadratic equation.