(1)4a*(-2b)-b^2*(-2b)
=-8ab+2b^3
(2)2x^2*x-2x^2*(1/2)
=2x^3-x^2
(3)5ab*2a-5ab*b+5ab*0.2
=10a^2b-5ab^2+ab
(4)2a^2*(-9a)-2/3a*(-9a)-4/9*(-9a)
=-18a^3+6a^2+4a
(1)4a*(-2b)-b^2*(-2b)
=-8ab+2b^3
(2)2x^2*x-2x^2*(1/2)
=2x^3-x^2
(3)5ab*2a-5ab*b+5ab*0.2
=10a^2b-5ab^2+ab
(4)2a^2*(-9a)-2/3a*(-9a)-4/9*(-9a)
=-18a^3+6a^2+4a