1/2+1/3+2/3+1/4+2/4+3/4+…+1/60+2/60+…+59/60.
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数学人气:734 ℃时间:2020-04-01 12:26:05
优质解答
12+13+23+14+24+34+…+160+260+…+5960,=12+(13+23)+(14+24+34)+…+(160+260+…+5960)=12+1+32+…+592=12+22+32+…+592=(1+2+3+4+…+59)÷2=(1+59)×59÷2÷2=60×59÷4=59×15=885.
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