计算①﹙2a＋3b﹚2·﹙3b－2a﹚②﹙z－2x－y﹚2－﹙﹣z＋2x＋y﹚2③﹙m＋2y﹚³④﹙3m－n﹚³

Question

计算①﹙2a＋3b﹚2·﹙3b－2a﹚ ②﹙z－2x－y﹚2－﹙﹣z＋2x＋y﹚2 ③﹙m＋2y﹚³ ④﹙3m－n﹚³

Answer 1

①﹙2a＋3b﹚2·﹙3b－2a﹚ ²
=[(3b+2a)(3b-2a)]²
=(9b²-4a²)²
=81b的4次方-72a²b²+16a的4次方
②﹙z－2x－y﹚2－﹙﹣z＋2x＋y﹚2
=(z-2x-y)²-(z-2x-y)²
=0
③﹙m＋2y﹚³
=m³+6m²y+12my²+8y³
④﹙3m－n﹚³=27m³-27m²n+9mn²-n³