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简算:19.99乘19.98-19.97乘19.96

来源:学生作业帮 编辑:搜搜考试网作业帮 分类:数学作业 时间:2024/05/14 08:51:05
简算:19.99乘19.98-19.97乘19.96
简算:19.99乘19.98-19.97乘19.96
19.99*19.98-19.97*19.96
=(19.97+0.02)*19.98-19.97*(19.98-0.02)
=(19.97*19.98+0.02*19.98)-(19.97*19.98-19.97*0.02)
=19.97*19.98+0.02*19.98-19.97*19.98+19.97*0.02
=0.02*19.98+19.97*0.02
=0.02*(19.98+19.97)
=0.02*(20-0.02+20-0.03)
=0.02*(40-0.05)
=0.02*40-0.02*0.05
=0.8-0.01
=0.799