WAEC - Mathematics (2001 - No. 20)

which of the following is not quadratic expression?

\(y = 2x^2 - 5x\)

\(y=x(x-5)\)

\(y = x^2 - 5\)

y = 5(x-1)

A quadratic equation is an equation of the second order. The highest power in the equation is 2.