Thực hiện phép tính (tính hợp lí nếu có thể): a) 1,56 + 8,44:4,22; b)5/7 + 4/(- 14)

a) \(1,56 + 8,44:4,22\)

\( = 1,56 + 2\)

\( = 3,56\)

c) \(\frac{2}{7} + \frac{5}{7}.\left( {\frac{3}{5} - \frac{1}{4}} \right).{\left( { - 2} \right)^2}\)

\( = \frac{2}{7} + \frac{5}{7}.\frac{7}{{20}}.4\)

\[ = \frac{2}{7} + 1\]\[ = \frac{9}{7}\].

b) \[\frac{5}{7} + \frac{4}{{ - 14}}\]

\[ = \frac{5}{7} + \frac{{ - 2}}{7}\]\[ = \frac{3}{7}\].

d) \(\frac{3}{4}.26\frac{2}{9} - 38\frac{2}{9}.\frac{3}{4}\)

\( = \frac{3}{4}.\left( {26\frac{2}{9} - 38\frac{2}{9}} \right)\)

\( = \frac{3}{4}.\left( {26 + \frac{2}{9} - 38 - \frac{2}{9}} \right)\)

\( = \frac{3}{4}.\left( { - 12} \right) =  - 9\).