Question

小升初数学简便计算解法

1/3+1/15+1/35+1/63+1/99+1/143

Answer 1

1/3+1/15+1/35+1/63+1/99+1/143
=1/1*3+1/3*5+1/5*7+1/7*9+1/9*11+1/11*13
=(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)/2
=(1-1/13)/2
=6/13

Answer 2

你好！
1/3+1/15+1/35+1/63+1/99+1/143
=(1-1/3)÷2+(1/3-1/5)÷2+(1/5-1/7)÷2+(1/7-1/9)÷2+(1/9-1/11)÷2+(1/11-1/13)÷2
=(1-1/3+1/3-1/5+1/5-1/7+1/7+1/9+1/9-1/11+1/11-1/13)÷2
=（1-1/13）÷2
=6/13

【希望可以帮到你】

Answer 3

1/3+1/15+1/35+1/63+1/99+1/143
=1/2x（1-1/3）+1/2x（1/3-1/5）+.....1/2x（1/9-1/11）+1/2（1/11-1/13）
=1/2x（1-1/3+1/3-1/5+....+1/9-1/11+1/11-1/13）
=1/2x（1-1/13）
=1/2x12/13
=6/13

Answer 4

拆项，合并。 上式=1/2X(1-1/3)+1/2X(1/3-1/5)+1/2X(1/5-1/7)+1/2X(1/7-1/9)+1/2X(1/9-1/11)+1/2X(1/111/13) =1/2X(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13) =1/2X(1-1/13)=1/2X12/13=6/13