Đáp án:
\(N = \dfrac{5}{{211}}\)
Giải thích các bước giải:
\(\begin{array}{l}
M = \dfrac{{631}}{{315}}.\dfrac{1}{{651}} - \dfrac{1}{{105}}.\dfrac{{2603}}{{651}} - \dfrac{4}{{315}}.\dfrac{1}{{651}} + \dfrac{4}{{105}}\\
= \dfrac{1}{{105}}.\left( { - \dfrac{{2603}}{{651}} + 4} \right) + \dfrac{1}{{651}}\left( {\dfrac{{631}}{{315}} - \dfrac{4}{{315}}} \right)\\
= \dfrac{1}{{105}}.\left( {\dfrac{{ - 2603 + 2604}}{{651}}} \right) + \dfrac{1}{{651}}.\dfrac{{627}}{{315}}\\
= \dfrac{1}{{105}}.\dfrac{1}{{651}} + \dfrac{1}{{651}}.\dfrac{{209}}{{105}}\\
= \dfrac{1}{{651}}\left( {\dfrac{1}{{105}} + \dfrac{{209}}{{105}}} \right)\\
= \dfrac{1}{{651}}.\dfrac{{210}}{{105}} = \dfrac{1}{{651}}.2 = \dfrac{2}{{651}}\\
N = \dfrac{{1095}}{{547}}.\dfrac{3}{{211}} - \dfrac{{546}}{{547}}.\dfrac{1}{{211}} - \dfrac{4}{{547}}.\dfrac{1}{{211}}\\
= \dfrac{1}{{211}}\left( {\dfrac{{1095.3}}{{547}} - \dfrac{{546}}{{547}} - \dfrac{4}{{547}}} \right)\\
= \dfrac{1}{{211}}.\dfrac{{3285 - 546 - 4}}{{547}}\\
= \dfrac{1}{{211}}.\dfrac{{2735}}{{547}} = \dfrac{1}{{211}}.5 = \dfrac{5}{{211}}
\end{array}\)
