Đáp án:
$\text{a)}$ $\dfrac{-2}{5}$
$\text{b)}$ $0$
$\text{c)}$ $\dfrac{-53}{101}$
Giải thích các bước giải:
$\text{a)}$ $\dfrac{-2}{3}$ $+$ $\dfrac{4}{15}$
$=$ $\dfrac{-10}{15}$ $+$ $\dfrac{4}{15}$
$=$ $\dfrac{-6}{15}$ $=$ $\dfrac{-2}{5}$
$\text{b)}$ $\dfrac{1}{3}$ $-$ $\dfrac{5}{4}$ $.$ $\dfrac{4}{15}$
$=$ $\dfrac{1}{3}$ $-$ $\dfrac{1}{3}$
$=$ $0$
$\text{c)}$ $\dfrac{53}{101}$ $.$ $\dfrac{-13}{97}$ $+$ $\dfrac{53}{101}$ $.$ $\dfrac{-84}{97}$
$=$ $\dfrac{53}{101}$ $.$ $($$\dfrac{-13}{97}$ $+$ $\dfrac{-84}{97}$$)$
$=$ $\dfrac{53}{101}$ $.$ $\dfrac{-97}{97}$
$=$ $\dfrac{53}{101}$ $.$ $-1$
$=$ $\dfrac{-53}{101}$
