2(x的3次方)的2次方乘以x的3次方-(3x的3次方)的3次方+(5x的2次方)的2次方乘以x的5次方
=2x的6次方×x³-27x的9次方+25x的4次方×x的5次方
=2x的9次方-27x的9次方+25的9次方
=0