Đáp án:
a) $\frac{2}{3}$ = $\frac{4}{6}$; $\frac{3}{2}$ = $\frac{6}{4}$; $\frac{6}{3}$ = $\frac{4}{2}$; $\frac{2}{4}$ = $\frac{3}{6}$.
b) $\frac{2}{8}$ = $\frac{9}{36}$; $\frac{2}{9}$ = $\frac{8}{36}$; $\frac{8}{2}$ = $\frac{36}{9}$; $\frac{36}{8}$ = $\frac{9}{2}$.
c) $\frac{-2}{4}$ = $\frac{7}{-14}$; $\frac{-2}{7}$ = $\frac{4}{-14}$; $\frac{4}{-2}$ = $\frac{-14}{7}$; $\frac{7}{-2}$ = $\frac{-14}{4}$.
Chúc học tốt!!!