Bài 1:
a. $\frac{15}{17}$ - $\frac{9}{17}$ = $\frac{15-9}{17}$ = $\frac{6}{17}$
$\frac{8}{7}$ - $\frac{5}{7}$ = $\frac{8-5}{7}$ = $\frac{3}{7}$
b;c: tự làm
Bài 2:
a. ; c. : tự làm
b. $\frac{2}{3}$ - $\frac{1}{2}$ = $\frac{4}{6}$ - $\frac{3}{6}$ = $\frac{4-3}{6}$ = $\frac{1}{6}$
$\frac{4}{3}$ - $\frac{2}{4}$ = $\frac{16}{12}$ - $\frac{6}{12}$ = $\frac{16-6}{12}$ = $\frac{10}{12}$ = $\frac{5}{6}$.
Bài 3:
$\frac{5}{8}$ + $\frac{4}{3}$ = $\frac{15}{24}$ + $\frac{32}{24}$ = $\frac{47}{24}$
$\frac{5}{7}$ - $\frac{2}{5}$ = $\frac{25}{35}$ - $\frac{14}{35}$ = $\frac{11}{35}$
$\frac{2}{5}$ + $\frac{5}{9}$ = $\frac{18}{45}$ + $\frac{25}{45}$ = $\frac{43}{45}$
$\frac{2}{3}$ - $\frac{4}{7}$ = $\frac{14}{21}$ - $\frac{12}{21}$ = $\frac{2}{21}$
Bài 4:
$\frac{3}{4}$ + $\frac{7}{12}$ = $\frac{9}{12}$ + $\frac{7}{12}$ = $\frac{16}{12}$ = $\frac{4}{3}$
$\frac{7}{4}$ - $\frac{7}{8}$ = $\frac{14}{8}$ - $\frac{7}{8}$ = $\frac{7}{8}$
$\frac{2}{7}$ + 4 = $\frac{2}{7}$ + $\frac{4}{1}$ =$\frac{2}{7}$ + $\frac{28}{7}$ = $\frac{30}{7}$
3 - $\frac{4}{5}$ = $\frac{3}{1}$ - $\frac{4}{5}$ = $\frac{15}{5}$ - $\frac{4}{5}$ = $\frac{11}{5}$
Bài 5:
$\frac{7}{8}$ - $\frac{5}{8}$ = $\frac{2}{8}$ = $\frac{1}{4}$
$\frac{5}{6}$ - $\frac{2}{3}$ = $\frac{5}{6}$ - $\frac{4}{6}$ = $\frac{1}{6}$
$\frac{3}{5}$ - $\frac{1}{4}$ = $\frac{12}{20}$ - $\frac{5}{20}$ = $\frac{7}{20}$
$\frac{25}{21}$ - $\frac{6}{7}$ = $\frac{25}{21}$ - $\frac{18}{21}$ = $\frac{7}{21}$ = $\frac{1}{3}$ .
#_Kaiz_
