7)
\(\dfrac{3}{7}.3\dfrac{5}{7}+\sqrt{\dfrac{9}{49}}.1\dfrac{2}{7}+\dfrac{6}{7}\)
\(=\dfrac{3}{7}.\dfrac{26}{7}+\dfrac{3}{7}.\dfrac{9}{7}+\dfrac{6}{7}\)
\(=\dfrac{3}{7}.\left(\dfrac{26}{7}+\dfrac{9}{7}\right)+\dfrac{6}{7}\)
\(=\dfrac{3}{7}.5+\dfrac{6}{7}\)
\(=\dfrac{15}{7}+\dfrac{6}{7}\)
\(=3\)
8)
\(\left\{\left[\left(\dfrac{1}{25}-0,6\right)^2:\dfrac{49}{125}\right].\dfrac{5}{6}\right\}-\left[\left(\dfrac{-1}{3}\right)+\dfrac{1}{2}\right]\)
\(=\left\{\left[\left(\dfrac{1}{25}-\dfrac{3}{5}\right)^2:\dfrac{49}{125}\right].\dfrac{5}{6}\right\}-\left[\left(\dfrac{-2}{6}\right)+\dfrac{3}{6}\right]\)
\(=\left\{\left[\left(\dfrac{1}{25}-\dfrac{15}{25}\right)^2:\dfrac{49}{125}\right].\dfrac{5}{6}\right\}-\dfrac{1}{6}\)
\(=\left\{\left[\left(\dfrac{-14}{25}\right)^2:\dfrac{49}{125}\right].\dfrac{5}{6}\right\}-\dfrac{1}{6}\)
\(=\left\{\left[\dfrac{196}{625}:\dfrac{49}{125}\right].\dfrac{5}{6}\right\}-\dfrac{1}{6}\)
\(=\left\{\left[\dfrac{196}{625}.\dfrac{125}{49}\right].\dfrac{5}{6}\right\}-\dfrac{1}{6}\)
\(=\left\{\dfrac{4}{5}.\dfrac{5}{6}\right\}-\dfrac{1}{6}\)
\(=\dfrac{2}{3}-\dfrac{1}{6}\)
\(=\dfrac{4}{6}-\dfrac{1}{6}\)
\(=\dfrac{1}{2}\)
