$\text{a/ $\dfrac{-5}{8}$ và $\dfrac{17}{-18}$}$
$\text{$\dfrac{17}{-18}$ = $\dfrac{-17}{18}$}$
$\text{Ta có: $\dfrac{5}{8}$ < $\dfrac{6}{8}$ = $\dfrac{3}{4}$}$
$\text{$\dfrac{17}{18}$ > $\dfrac{16}{18}$ = $\dfrac{8}{9}$}$
$\text{$\dfrac{3}{4}$ = 1 - $\dfrac{1}{4}$}$
$\text{$\dfrac{8}{9}$ = 1 - $\dfrac{1}{9}$}$
$\text{$\dfrac{1}{4}$ > $\dfrac{1}{9}$}$
$\text{nên 1 - $\dfrac{1}{4}$ < 1 - $\dfrac{1}{9}$}$
$\text{⇒ $\dfrac{3}{4}$ < $\dfrac{8}{9}$}$
$\text{$\dfrac{5}{8}$ < $\dfrac{3}{4}$ < $\dfrac{8}{9}$ < $\dfrac{17}{18}$}$
$\text{nên $\dfrac{5}{8}$ < $\dfrac{17}{18}$}$
$\text{⇒ $\dfrac{-5}{8}$ > $\dfrac{17}{-18}$}$
$\text{Vậy $\dfrac{-5}{8}$ = $\dfrac{17}{-18}$}$
$\text{b/ $\dfrac{8}{-15}$ và $\dfrac{-2}{3}$}$
$\text{Ta có: $\dfrac{8}{-15}$ = $\dfrac{-8}{15}$ > $\dfrac{-10}{15}$ = $\dfrac{-2}{3}$}$
$\text{nên $\dfrac{8}{-15}$ > $\dfrac{-2}{3}$}$
$\text{Vậy $\dfrac{8}{-15}$ > $\dfrac{-2}{3}$}$
$\text{HỌC TỐT NHÓ!}$
$Hry_{123}$
