Thực hiện phép tính a, 5/17 + -15/34 x 2/5 b, (-2/5 + 1/3) x (3/2-3/7) c, 1/2 x 5/6 + 2/3 x 3/4 d, (1+1/2) x (1+1/3) x (1+1

Giải đáp:$\begin{array}{l}
a)\dfrac{2}{{17}}\\
b) – \dfrac{1}{{14}}\\
c)\dfrac{{11}}{{12}}\\
d)\dfrac{5}{2}
\end{array}$

 

Lời giải và giải thích chi tiết:

$\begin{array}{l}
a)\dfrac{5}{{17}} + \dfrac{{ – 15}}{{34}}.\dfrac{2}{5}\\
 = \dfrac{5}{{17}} + \dfrac{{ – 3}}{{17}}\\
 = \dfrac{2}{{17}}\\
b)\left( {\dfrac{{ – 2}}{5} + \dfrac{1}{3}} \right).\left( {\dfrac{3}{2} – \dfrac{3}{7}} \right)\\
 = \dfrac{{ – 1}}{{15}}.\dfrac{{15}}{{14}}\\
 =  – \dfrac{1}{{14}}\\
c)\dfrac{1}{2}.\dfrac{5}{6} + \dfrac{2}{3}.\dfrac{3}{4}\\
 = \dfrac{5}{{12}} + \dfrac{6}{{12}}\\
 = \dfrac{{11}}{{12}}\\
d)\left( {1 + \dfrac{1}{2}} \right).\left( {1 + \dfrac{1}{3}} \right).\left( {1 + \dfrac{1}{4}} \right)\\
 = \dfrac{3}{2}.\dfrac{4}{3}.\dfrac{5}{4}\\
 = \dfrac{5}{2}
\end{array}$