1+3+5+7+9+.+(2n-1)+(2n+1)

1+3+5+7+9+.+(2n-1)+(2n+1)+(2n+3)=

14个回答

1+2+3+4+5+6+7+8+9+…+n=n(n+1)/2 1+3+5+7+9+11+13+15+…+(2n-1)=n
1+3+5+7+9+.+(2n-1)+(2n+1)=
1/1*5+1/3*7+1/5*9+.+1/(2n-1)(2n+3)
数列求和Sn=1/1*3+4/3*5+9/5*7+……n^2/(2n-1)(2n+1)
求和：Sn=(1/3*5)+(1/5*7)+(1/7*9)+...+[1/(2n+1)(2n+3)]
1/1*3+1/3*5+1/5*7+.+1/（2n-1）(2n+1)=n/(2n+1)
3+5+7+9.+(2n+1)=168,n=?
3/2*5/4*7/6*9/8*...2n+1/2n>根号n+1
1*2+2*3+3*4+4*5+5*6+6*7+…+n(n+1)=n(n+1)(n+2)/3
1/1*3+1/5*7+ 1/9*11+.1/(2n-1)(2n+1)