Answer
$x^2-4x=0$
Work Step by Step
Write the quadratic as the product of two linear factors and the leading coefficient: $a(x-r_1)(x-r_2)=0$, where $r_1$ and $r_2$ are the solutions.
$a(x-0)(x-4)=0~~$ (Make $a=1$ since it can be any real number except $0$)
$x(x-4)=0$
$x^2-4x=0$ (general form)
