Question

\(\dfrac{1}{7}+\dfrac{1}{91}+\dfrac{1}{247}+\dfrac{1}{475}+\dfrac{1}{775}+\dfrac{1}{1147}\)

Answer 1

=1/1*7+1/7*13+1/13*19+1/19*25+1/25*31+1/31*37

=1/6(6/1*7+6/7*13+...+6/31*37)

=1/6(1-1/7+1/7-1/13+...+1/31-1/37)

=1/6*36/37=6/37