CHÚC BẠN HỌC TỐT!!!
Đáp án:
$a, 0$
$b, -1$
Giải thích các bước giải:
$a, \dfrac{-1}{2}+\dfrac{3}{5}-\dfrac{7}{18}-\dfrac{-2}{7}-\dfrac{1}{9}+\dfrac{4}{35}$
$=\bigg{(}\dfrac{-1}{2}-\dfrac{7}{18}-\dfrac{1}{9}\bigg{)}+\bigg{(}\dfrac{3}{5}-\dfrac{-2}{7}+\dfrac{4}{35}\bigg{)}$
$=\bigg{(}\dfrac{-9}{18}-\dfrac{7}{18}-\dfrac{2}{18}\bigg{)}+\bigg{(}\dfrac{21}{35}+\dfrac{10}{35}+\dfrac{4}{35}\bigg{)}$
$=-\dfrac{18}{18}+\dfrac{35}{35}$
$=-1+1=0$
$b, \dfrac{1}{3}+\dfrac{-7}{4}+\dfrac{1}{15}-\dfrac{2}{9}-\dfrac{-3}{5}-\dfrac{1}{36}$
$=\bigg{(}\dfrac{1}{3}+\dfrac{1}{15}-\dfrac{-3}{5}\bigg{)}+\bigg{(}\dfrac{-7}{4}-\dfrac{2}{9}-\dfrac{1}{36}\bigg{)}$
$=\bigg{(}\dfrac{5}{15}+\dfrac{1}{15}+\dfrac{9}{15}\bigg{)}-\bigg{(}\dfrac{63}{36}-\dfrac{8}{36}-\dfrac{1}{36}\bigg{)}$
$=\dfrac{15}{15}-\dfrac{72}{36}$
$=1-2=-1$
