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简便方法计算,急(3/5-1/2-7/12)乘(60*3/7-60*1/7+60*5/7)= 13除1.5-0.34除3

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/11/08 20:46:40
简便方法计算,急
(3/5-1/2-7/12)乘(60*3/7-60*1/7+60*5/7)= 13除1.5-0.34除3又1/3+1/3除1/13-0.34除1又2/5= -149又3/40乘20= 99又24/25乘(-5)= 全部用简便方法计算!急,
(3/5-1/2-7/12)乘(60*3/7-60*1/7+60*5/7) =(3/5-1/2-7/12)乘(3/7-1/7+5/7)×60 =(3/5-1/2-7/12)×1×60 =3/5×60-1/2×60-7/12×60 =36-30-35 = -29 13除1.5-0.34除3又1/3+1/3除1/13-0.34除1又2/5 =13除3/2-0.34除10/3+1/3除1/13-0.34除7/5 =13×2/3-0.34×3/10+1/3×13-0.34×5/7 =13×2/3+1/3×13-0.34×3/10-0.34×5/7 =13×(2/3+1/3)-0.34×(3/10+5/7) =13-0.34×71/70 -149又3/40乘20 =(-149-3/40)乘20 = -298-3/2 = -299-1/2 =-299又1/2 99又24/25乘(-5) =99×(-5)+24/25×(-5) = -495-24/5 = -499-4/5 = -499又4/5