Cho \[M = \frac{5}.\frac{{ - 31}}.\frac{1}{2}.\frac.{\left( {\frac{{ - 1}}{2}} \right)^3}\] và \[N = \left( {\frac + \frac - \frac - \frac} \right).\left( {\frac{{ - 5}} + \frac{1}{4} + \frac{1}{6}} \right)\]. Khi đó, tổng M + N bằng

Trả lời:

\[M = \frac{5}.\frac{{ - 31}}.\frac{1}{2}.\frac.{\left( {\frac{{ - 1}}{2}} \right)^3}\]

\[M = \frac{{17.\left( { - 31} \right).1.10.{{\left( { - 1} \right)}^3}}}{{{{5.125.2.17.2}^3}}}\]

\[M = \frac{{ - 31.\left( { - 1} \right)}}{{{{125.2}^3}}}\]

\[M = \frac\]

\[N = \left( {\frac + \frac - \frac - \frac} \right).\left( {\frac{{ - 5}} + \frac{1}{4} + \frac{1}{6}} \right)\]

\[N = \left( {\frac + \frac - \frac - \frac} \right).\left( {\frac{{ - 5}} + \frac{3} + \frac{2}} \right)\]

\[N = \left( {\frac + \frac - \frac - \frac} \right).0\]

N = 0

Vậy \[M + N = \frac + 0 = \frac\]

Đáp án cần chọn là: B