“ ^ ”代表次方
[-3(a+b)^2]^3 x [2(a+b)^3]^2
=(-3)^3 x (a+b)^6 x 2^2 x (a+b)^6
= -108(a+b)^12（x·x³）的5次方·x²=(x^4)^5 * x^2
=x^20 * x^2
=x^22