计算:(a+2b-3c)(a-2b+3c)要过程,谢

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计算:(a+2b-3c)(a-2b+3c)要过程,谢
计算:(a+2b-3c)(a-2b+3c)要过程,谢

计算:(a+2b-3c)(a-2b+3c)要过程,谢
:(a+2b-3c)(a-2b+3c)
=[a+(2b-3c)][a-(2b-3c)]
=a²-(2b-3c)²
=a²-(4b²-12bc+9c²)
=a²-4b²+12bc-9c²

原式=[a+(2b-3c)][a-(2b-3c)]
=a²-(2b-3c)²
=a²-(4b²-12bc+9c²)
=a²-4b²+12bc-9c²

=[a+(2b-3c)][a-(2b-3c)]
=a²+4b²+9c²-12bc

(a+2b-3c)(a-2b+3c)
=[a+(2b-3c)][a-(2b-3c)]
=a²-(2b-3c)²
=a²-(4b²-12bc+9c²)
=a²-4b²+12bc-9c²