1. Thực hiện phép tính (tính hợp lý nếu có thể): (a) − 3/ 4 + 4/ 5 . − 5/ 2

1.

a) \[\frac{{ - 3}}{4} + \frac{4}{5}\,\,.\,\,\frac{{ - 5}}{2} = \frac{{ - 3}}{4} - 2 = \frac{{ - 11}}{4}\];

b) \(\frac{{ - 1}}{{18}}\,\,.\,\,\frac{{ - 7}}{2} + \frac{{ - 1}}{{18}}\,\,.\,\,\frac{3}{2} = \frac{{ - 1}}{{18}}\,\,.\,\,\left( {\frac{{ - 7}}{2} + \frac{3}{2}} \right) = \frac{{ - 1}}{{18}}\,\,.\,\,\left( { - 2} \right) = \frac{1}{9}\).

2.

a) \(\frac{8}{5}:x - \frac{3}{{10}} = \frac{7}{6}\)

\(\frac{8}{5}:x = \frac{7}{6} + \frac{3}{{10}}\)

\(\frac{8}{5}:x = \frac{{22}}{{15}}\)

\(x = \frac{8}{5}:\frac{{22}}{{15}}\)

\(x = \frac{{12}}{{11}}\)

Vậy \(x = \frac{{12}}{{11}}\).

b) \({\left( {3x - 1} \right)^{2\,\,022}} = {\left( {4x + 5} \right)^{2\,\,022}}\)

\(3x - 1 = 4x + 5\)

\(4x - 3x = - 1 - 5\)

\(x = - 6\)

Vậy \(x = - 6\).