Thực hiện phép tính: b) ( − 1 /2 ) ^2 ⋅ 2 6/ 7 − 14 /15 : 2 1/ 3 + ( − 1 , 21 )^ 0 ;

b) \({\left( { - \frac{1}{2}} \right)^2} \cdot 2\frac{6}{7} - \frac{{14}}{{15}}:2\frac{1}{3} + {\left( { - 1,21} \right)^0}\)

\( = \frac{1}{4} \cdot \frac{{20}}{7} - \frac{{14}}{{15}}:\frac{7}{3} + 1 = \frac{5}{7} - \frac{2}{5} + 1 = \frac{{46}}{{35}}\);