原式=[4a^nb^(n-1)×(-6a³b^4)+(-3a^nb^n)×(-2)³×a³×b³]÷3ab=[4×(-6)×a^n×a³×b^(n-1)×b^4+(-3)×(-8)×a^n×a³×b^n×b³]÷3ab=[-24a^(n+3)×b^(n+3)+24a^(n+3)×b^(n+...