Thực hiện phép tính (Tính hợp lí nếu có thể 2*(-5)+48:2^3
Hướng dẫn giải
a) \(2 \cdot \left( { - 5} \right) + 48:{2^3}\) \( = 2 \cdot \left( { - 5} \right) + 48:8\) \( = - 10 + 6\) \( = - 4\). | b) \(\frac{5}{{11}} + \frac{6}{{11}}:\frac{6}{7}\) \( = \frac{5}{{11}} + \frac{6}{{11}} \cdot \frac{7}{6}\) \( = \frac{5}{{11}} + \frac{7}{{11}}\) \( = \frac{{12}}{{11}}.\) |
c) \(\left( { - 10} \right):\left( { - 2} \right) + \left( {3,2 - 8,6} \right)\) \( = 5 + \left( { - 5,4} \right)\) \( = 5 - 5,4\) \( = 0,4\). | d) \(\frac{3}{4} \cdot \left( {\frac{{ - 13}}{{21}} + \frac{5}{{27}}} \right) + 0,75 \cdot \left( {\frac{{ - 8}}{{21}} + \frac{6}{{27}}} \right)\) \( = \frac{3}{4} \cdot \left( {\frac{{ - 13}}{{21}} + \frac{5}{{27}}} \right) + \frac{3}{4} \cdot \left( {\frac{{ - 8}}{{21}} + \frac{6}{{27}}} \right)\) \( = \frac{3}{4} \cdot \left( {\frac{{ - 13}}{{21}} + \frac{5}{{27}} + \frac{{ - 8}}{{21}} + \frac{6}{{27}}} \right)\) \( = \frac{3}{4} \cdot \left[ {\left( {\frac{{ - 13}}{{21}} + \frac{{ - 8}}{{21}}} \right) + \left( {\frac{5}{{27}} + \frac{6}{{27}}} \right)} \right]\) \( = \frac{3}{4} \cdot \left[ { - 1 + \frac{{11}}{{27}}} \right]\) \( = \frac{3}{4} \cdot \left( {\frac{{ - 16}}{{27}}} \right)\) \( = \frac{{ - 4}}{9}.\) |