Question

1/7+1/51+1/247+1/475+1/775

Answer 1

A=1/7 +1/91 +1/247 + 1/475 + 1/775 + 1/1147 
A=1/(1.7)+1/(7.13)+1/(13.19)+...+1/(31... 
A=(1/6)*( 1 - 1/7 + 1/7 - 1/13 +... +1/31-1/37) 
A=(1/6)*(1-1/37) 
A=(1/6)*(36/37) 
A=6/37 
. 

Answer 2

còn nữa chứ

Tính tổng 1/7 +1/91 +1/247 + 1/475 + 1/775 + 1/1147

A=1/7 +1/91 +1/247 + 1/475 + 1/775 + 1/1147 
A=1/(1.7)+1/(7.13)+1/(13.19)+...+1/(31... 
A=(1/6)*( 1 - 1/7 + 1/7 - 1/13 +... +1/31-1/37) 
A=(1/6)*(1-1/37) 
A=(1/6)*(36/37) 
A=6/37