Video solusi : (1)/(akar(2)-1)-(1)/(akar(2)+1)+(1)/(akar(3)-1)-(1)/(akar(3)+1)+(1)/(akar(4)-1)-(1)/(akar(4)+1)+...+(1)/(akar(20)-1)-1/(akar(20)+1)=... A. sigma n=1 21 2/n
C. sigma n=1 21 1/n
E. sigma n=1 20 2/n
B. sigma n=1 20 1/n
D. sigma n=1 19 2/n