a+1分之a-a的平方-1分之a-2除以a的平方-2a+1分之a的平方-2a
2个回答

原式=[a/(a+1)]-[(a-2)/(a²-1)]÷[(a²-2a)/(a²-2a+1)]

=[a/(a+1)]-[(a-2)/(a²-1)]÷[a(a-2)/(a-1)²]

=[a/(a+1)]-[(a-2)/(a²-1)]×{ (a-1)²/[a(a-2)] }

=[a/(a+1)]- { (a-2)/[(a+1)(a-1)] }×{ (a-1)²/[a(a-2)] }

=[a/(a+1)]-{ (a-1)/[a(a+1)] }

={ a²/[a(a+1)] }-{ (a-1)/[a(a+1)] }

=[a²-(a-1)]/[a(a+1)]

=(a²-a+1)/(a²+a)

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