1/2+(1/3+2/3)+(1/4+2/4+3/4)+.+(1/50+2/50+3/50+.+48/50+49/50) 怎么算?
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![1/2+(1/3+2/3)+(1/4+2/4+3/4)+.+(1/50+2/50+3/50+.+48/50+49/50) 怎么算?](/uploads/image/z/7134978-66-8.jpg?t=1%2F2%2B%EF%BC%881%2F3%2B2%2F3%EF%BC%89%2B%EF%BC%881%2F4%2B2%2F4%2B3%2F4%EF%BC%89%2B.%2B%EF%BC%881%2F50%2B2%2F50%2B3%2F50%2B.%2B48%2F50%2B49%2F50%EF%BC%89+%E6%80%8E%E4%B9%88%E7%AE%97%3F)
1/2+(1/3+2/3)+(1/4+2/4+3/4)+.+(1/50+2/50+3/50+.+48/50+49/50) 怎么算?
1/2+(1/3+2/3)+(1/4+2/4+3/4)+.+(1/50+2/50+3/50+.+48/50+49/50) 怎么算?
1/2+(1/3+2/3)+(1/4+2/4+3/4)+.+(1/50+2/50+3/50+.+48/50+49/50) 怎么算?
括号里的通式为(1+2+3+…+n-1)/n简化为(n-1)/2所以原式可化为1/2+(3-1)/2+(4-1)/2+…+(50-1)/2=(1+2+3+…+49)/2=1225