57X55/56+27X27/28 简便运算 - 知识问答

57X55/56+27X27/28 简便运算

3个回答

原式=（55+2)*55/56+(25+2)(25+2)/28
=(55*55+2*55)/56+2*(25*25+2*2*25+2*2)/56
=(3025+110)/56+2*(625+100+4)/56
=3135/56+2*729/56
=(3135+1458)/56
=4593/56

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