Hi can someone please help
Which expressions are completely factored?

18x^4−12x^2=6x(3x^3−2x)

24x^6−18x^5=6x^5(4x−3)

12x^5+8x^3=2x^3(6x^2+4)

20x^3+12x^2=4x^2(5x+3)