Ta có 1152-(374+1152)+(-65+374)

=1152-374-1152+(-65)+374

=(1152-1152)+(-374+374)+(-65)

=-65

77 x 12+77+77 x 87

=77 x (12+1+87)

=77 x 100

=7700

GIUP MIK NHA CAC BAN

B=\(\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2013}\right):\left(2012+\dfrac{2011}{2}+...+\dfrac{2}{2011}+\dfrac{1}{2012}\right)\).Tính B