Question

57乘56分之55加27乘28分之27怎么做？

用简便方法做！速度急要

Answer 1

57*（55/56）+（28-1）*(27/28)
=(56 + 1)*(55/56) + （28-1） * (27/28 )
=55 + 55/56 + 27 - 27/28 = 82又56分之1

Answer 2

57*55/56 +27*27/28
=(56+1)(56-1)/56+(28-1)*(28-1)/28
=(56^2-1)/56+(28^2-2*28+1)/28
=56-1/56+28-2+1/28
=82-1/56+2/56
=82又1/56

Answer 3

57*(55/56)+27*(27/28)
=57*（1-1/56）+27*（1-1/28）
=57-57/56+27-27/28
=(57+27)-(57/56+27/28)
=84-1又55/56
=82又1/56

Answer 4

(56+1)*55/56+(28-1)*27/28
=55+55/56+27-27/28
=82+(55/56-54/56)
=82/56
=41/28