Giải thích các bước giải:
\(\begin{array}{l}
a) = {\left( {\dfrac{2}{6} - \dfrac{3}{6}} \right)^2} - \dfrac{1}{6} = {\left( { - \dfrac{1}{6}} \right)^2} - \dfrac{1}{6}\\
= \dfrac{1}{{36}} - \dfrac{1}{6} = \dfrac{{ - 5}}{{36}}\\
b) = \dfrac{4}{7} - \dfrac{1}{{14}} + \dfrac{5}{{21}} + \dfrac{3}{7}\\
= \left( {\dfrac{4}{7} + \dfrac{3}{7}} \right) + \dfrac{5}{{21}} - \dfrac{1}{{14}}\\
= 1 + \dfrac{{10}}{{42}} - \dfrac{3}{{42}} = 1 + \dfrac{7}{{42}} = 1 + \dfrac{1}{6} = \dfrac{7}{6}\\
c) = \dfrac{1}{9} - \dfrac{1}{9}:\dfrac{5}{9} + 1.1\\
= \dfrac{1}{9} - \dfrac{1}{9}.\dfrac{9}{5} + 1 = \dfrac{1}{9} - \dfrac{1}{5} + 1\\
= \dfrac{{ - 4}}{{45}} + 1 = \dfrac{{41}}{{45}}\\
d) = \left[ {0,25 - \left( {\dfrac{{ - 2}}{3} + \dfrac{5}{4}} \right):\dfrac{{25}}{9}} \right] - {\left( {4,5 - 6,5} \right)^2}\\
= \left( {0,25 - \dfrac{7}{{12}}.\dfrac{9}{{25}}} \right) - {2^2}\\
= \left( {0,25 - 0,07} \right) - 4 = 0,18 - 4 = - 3,82\\
2)a)x = \dfrac{4}{9} - \left( { - \dfrac{5}{8}} \right)\\
x = \dfrac{4}{9} + \dfrac{5}{8}\\
x = \dfrac{{32 + 45}}{{72}}\\
x = \dfrac{{77}}{{72}}\\
b)\dfrac{2}{3}x - \dfrac{1}{4} = \dfrac{3}{4}\\
\dfrac{2}{3}x = \dfrac{3}{4} + \dfrac{1}{4}\\
\dfrac{2}{3}x = 1\\
x = 1:\dfrac{2}{3}\\
x = \dfrac{3}{2}\\
c)\left| {x - \dfrac{1}{2}} \right| = 2\dfrac{1}{3} - \dfrac{1}{3}\\
\left| {x - \dfrac{1}{2}} \right| = 2\\
TH1:x - \dfrac{1}{2} = 2\\
x = \dfrac{1}{2} + 2\\
x = \dfrac{5}{2}\\
TH2:x - \dfrac{1}{2} = - 2\\
x = - 2 + \dfrac{1}{2}\\
x = - \dfrac{3}{2}\\
d){\left( {\dfrac{3}{5}} \right)^{2x}} = {\left( {\dfrac{3}{5}} \right)^{10}}:{\left( {\dfrac{3}{5}} \right)^8}\\
{\left( {\dfrac{3}{5}} \right)^{2x}} = {\left( {\dfrac{3}{5}} \right)^2}\\
2x = 2\\
x = 1
\end{array}\)
