for,
24x - 6x^2 = 0 ................ 6x(4 - x) = 0
solution is x = 0, x = 4
For ,
2x^2 + 6x = 0 .................. 2x(x + 3) = 0
solution is x = 0, x = -3
For,
14x - 7x^2 = 0 .................. 7x(2 - x) = 0
solution x = 0, x = 2
For,
4x - x^2 = 0 ........................ x(4 - x) = 0
solution x = 0, x = 4