化简求值﹙﹣x＋3y﹚²﹙﹣x－3y﹚²－﹙2x－y﹚²﹙﹣2x－y﹚²,其中x＝﹣2,y＝½
问题描述：
化简求值﹙﹣x＋3y﹚²﹙﹣x－3y﹚²－﹙2x－y﹚²﹙﹣2x－y﹚²,其中x＝﹣2,y＝½
答
﹙﹣x＋3y﹚²﹙﹣x－3y﹚²－﹙2x－y﹚²﹙﹣2x－y﹚²,其中x＝﹣2,y＝½
=﹙x-3y﹚²﹙x+3y﹚²－﹙2x－y﹚²﹙2x+y﹚²
=(x²-9y²)²-(4x²-y²)²
=(x²-9y²+4x²-y²)(x²-9y²-4x²+y²)
=(5x²-10y²)(-3x²-8y²)
=(20-2.5)(-12-2)
=(20-2.5)(-14)
=-280+35
=-245