3(x^4)^6-2(x^5×x^3)^3+x^11×x^13+x^20×x^3×x
=3x^24-2(x^8)^3+x^24+x^24
=3x^24-2x^24+x^24+x^24
=x^24(3-2+1+1)
=3x^24