-(2xy)^3+(-3xy)^3 =-8x^3y^3-27x^3y^3=-35x^3y^3(5ab)^2+(3ab)^2=25a²b²+9a²b²=34a²b²8^2012*1/8^2013=8^2012*1/8^2012×1/8=(8*1/8)^2012×1/8=1/8(-4a^2)^3+(-4a^3)^2=-64a^6+16a^...还有一个哦，还有请问-x^21+-x^21=？-a·a^5-(a^2)^3-(-2a^3)^2=-a^6-a^6-4a^6=-6a^6-x^21+-x^21=？2（a^2)^3*a^3-(3a^3)^3+(5a^7)a^2谢谢了，加分哦~-x^21+-x^21没有+-的 -x^21+(-x)^21 =-x^21-x^21=-2x^21 2（a^2)^3*a^3-(3a^3)^3+(5a^7)a^2=2a^9-27a^9+5a^9=-20a^9