f(x)=x(x+4)(x-4)
f(x)=(x+1)(x+3)(x-3)
f(x)=x(x+1)(x-1)
f(x)=x^2(x+4)(x-4)
f(x)=(x-1)(x+1)(x-1)
f(x)=x(x-4)(x-2)
f(x)=x(x-2)(x-2)
f(x)=x^2(x+4)(x-1)
f(x)=(x+2)(x+1)(x-2)(x-1)
