Question

7分之3+35分之1+63分之1+99分之1+143分之1

Answer 1

3/7 + 1/35 + 1/63 + 1/99 + 1/143

= 3/7 + (1/2)(1/5 - 1/7) + (1/2)(1/7 -1/9) + (1/2)(1/9 - 1/11) + (1/2)(1/11 - 1/13)

= 3/7 + (1/2)(1/5) -(1/2)(1/13)

= 3/7 + 1/10 -1/26

= 30/70 + 7/70 - 1/26

= 37/70 - 1/26

= 481/910 - 35/910

=446/910 = 223/455