﹙m+1﹚²-9﹙m-1﹚²=[﹙m+1﹚+3﹙m-1﹚]·[﹙m+1﹚-3﹙m-1﹚]
=[4m-2]·[-2m+4]
=-4﹙2m-1﹚﹙m-2﹚
a²﹙x-1﹚+b²﹙1-x﹚=a²﹙x-1﹚-b²﹙x-1﹚
=﹙x-1﹚﹙a²-b²﹚
=﹙x-1﹚﹙a-b﹚﹙a+b﹚
﹙m+1﹚²-9﹙m-1﹚²=[﹙m+1﹚+3﹙m-1﹚]·[﹙m+1﹚-3﹙m-1﹚]
=[4m-2]·[-2m+4]
=-4﹙2m-1﹚﹙m-2﹚
a²﹙x-1﹚+b²﹙1-x﹚=a²﹙x-1﹚-b²﹙x-1﹚
=﹙x-1﹚﹙a²-b²﹚
=﹙x-1﹚﹙a-b﹚﹙a+b﹚