\(a,12.\left(-\dfrac{2}{3}\right)^2+\dfrac{3}{4}\\ =12.\dfrac{4}{9}+\dfrac{3}{4}\\ \dfrac{16}{3}+\dfrac{3}{4}\\ =\dfrac{73}{12}\\ b,\dfrac{2}{5}.\left(\dfrac{-2}{7}\right)+\dfrac{2}{5}.\left(\dfrac{-5}{7}\right)\\ =\dfrac{2}{5}.\left(\dfrac{-2}{7}+\dfrac{-5}{7}\right)\\ =\dfrac{2}{5}.-1\\ =\dfrac{-2}{5}\)
a)
\(12.\left(-\dfrac{2}{3}\right)^2+\dfrac{3}{4}\)
\(=12.\dfrac{4}{9}+\dfrac{3}{4}\)
\(=\dfrac{16}{3}+\dfrac{3}{4}\)
\(=\dfrac{64}{12}+\dfrac{9}{12}\)
\(=\dfrac{73}{12}\)
b)
\(\dfrac{2}{5}.\left(\dfrac{-2}{7}\right)+\dfrac{2}{5}.\left(\dfrac{-5}{7}\right)\)
\(=\dfrac{2}{5}.\left(\dfrac{-2}{7}+\dfrac{-5}{7}\right)\)
\(=\dfrac{2}{5}.\left(-1\right)\)
\(=\dfrac{-2}{5}\)
