用简便方法计算2+7+12+17+.192+197
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/10 18:11:38
用简便方法计算2+7+12+17+.192+197
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帮忙解答急用
![用简便方法计算2+7+12+17+.192+197](/uploads/image/z/7494190-70-0.jpg?t=%E7%94%A8%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95%E8%AE%A1%E7%AE%972%2B7%2B12%2B17%2B.192%2B197)
2+7+12+17+.192+197
=2+12+22+32+.+192+7+17+27+.+197
=(2+192)*20/2+(7+197)*20/2
=194*10+204*10
=1940+2040
=3980
=2+12+22+32+.+192+7+17+27+.+197
=(2+192)*20/2+(7+197)*20/2
=194*10+204*10
=1940+2040
=3980