Đáp án:
\(\dfrac{113}{210}\)
Giải thích các bước giải:
\(\dfrac{1}{6}-\dfrac{2}{5}+\dfrac{9}{7}.\dfrac{3}{5}\\ = \left ( \dfrac{1.5}{6.5} - \dfrac{2.6}{5.6} \right ) +\dfrac{9.3}{7.5}\\ =\left ( \dfrac{5}{30} - \dfrac{12}{30} \right ) + \dfrac{27}{35}\\ =\dfrac{5-12}{30}+\dfrac{27}{35}\\ =\dfrac{-7}{30}+\dfrac{27}{35}\\ =\dfrac{(-7).7}{30.7}+\dfrac{27.6}{35.6}\\ =\dfrac{-49}{210}+\dfrac{162}{210}\\ =\dfrac{(-49)+162}{210}\\ =\dfrac{113}{210}\)
chúc bạn học tốt!
