Bài 1 điền dấu lớn dấu bé dấu bằng vào chỗ chấm

1/2....... 1/12. 5/7.......... 5/9

2/3........ 3/4. 8/9............ 7/8

Bài 2 so sánh các phân số

2/3 , 3/5 , 4/9 , 5/12 , 7/17 với 1/2

Bài $\text{1:}$

$\dfrac{1}{2}$ và $\dfrac{1}{12}$ $\text{(}$ MSC $\text{:24 )}$

$\dfrac{1}{2}$ = $\dfrac{1 \times 12}{2 \times 12}$ = $\dfrac{12}{24}$ ; $\dfrac{1}{12}$ = $\dfrac{1 \times 2}{12 \times 2}$ = $\dfrac{2}{24}$

Vì $\text{12 > 2}$ nên $\dfrac{1}{2}$ $\text{>}$ $\dfrac{1}{12}$

$\dfrac{1}{2}$ $\text{>}$ $\dfrac{1}{12}$

_____________________________________________________________________

$\dfrac{5}{7}$ và $\dfrac{5}{9}$ $\text{(}$ MSC $\text{:63 )}$

$\dfrac{5}{7}$ = $\dfrac{5 \times 9}{7 \times 9}$ = $\dfrac{45}{63}$ ; $\dfrac{5}{9}$ = $\dfrac{5 \times 7}{9 \times 7}$ = $\dfrac{35}{63}$

Vì $\text{45 > 35}$ nên $\dfrac{5}{7}$ $\text{>}$ $\dfrac{5}{9}$

$\dfrac{5}{7}$ $\text{>}$ $\dfrac{5}{9}$

_____________________________________________________________________

$\dfrac{2}{3}$ và $\dfrac{3}{4}$ $\text{(}$ MSC $\text{:12 )}$

$\dfrac{2}{3}$ = $\dfrac{2 \times 4}{3 \times 4}$ = $\dfrac{8}{12}$ ; $\dfrac{3}{4}$ = $\dfrac{3 \times 3}{4 \times 3}$ = $\dfrac{9}{12}$

Vì $\text{8 < 9}$ nên $\dfrac{2}{3}$ $\text{<}$ $\dfrac{3}{4}$

$\dfrac{2}{3}$ $\text{<}$ $\dfrac{3}{4}$

_____________________________________________________________________

$\dfrac{8}{9}$ và $\dfrac{7}{8}$ $\text{(}$ MSC $\text{:72 )}$

$\dfrac{8}{9}$ = $\dfrac{8 \times 8}{9 \times 8}$ = $\dfrac{64}{72}$ ; $\dfrac{7}{8}$ = $\dfrac{7 \times 9}{8 \times 9}$ = $\dfrac{63}{72}$

Vì $\text{64 > 63}$ nên $\dfrac{8}{9}$ $\text{>}$ $\dfrac{7}{8}$

$\dfrac{8}{9}$ $\text{>}$ $\dfrac{7}{8}$

_____________________________________________________________________

Bài $\text{2:}$

$\dfrac{2}{3}$ và $\dfrac{1}{2}$ $\text{(}$ MSC$\text{ :6 )}$

$\dfrac{2}{3}$ = $\dfrac{2 \times 2}{3 \times 2}$ = $\dfrac{4}{6}$ ; $\dfrac{1}{2}$ = $\dfrac{1 \times 3}{2 \times 3}$ = $\dfrac{3}{6}$

Vì $\text{4 > 3}$ nên $\dfrac{2}{3}$ $\text{>}$ $\dfrac{1}{2}$

$\dfrac{2}{3}$ $\text{>}$ $\dfrac{1}{2}$

_____________________________________________________________________

$\dfrac{3}{5}$ và $\dfrac{1}{2}$ $\text{(}$ MSC$\text{ :10 )}$

$\dfrac{3}{5}$ = $\dfrac{3 \times 2}{5 \times 2}$ = $\dfrac{6}{10}$ ; $\dfrac{1}{2}$ = $\dfrac{1 \times 5}{2 \times 5}$ = $\dfrac{5}{10}$

Vì $\text{6 > 5}$ nên $\dfrac{3}{5}$ $\text{>}$ $\dfrac{1}{2}$

$\dfrac{3}{5}$ $\text{>}$ $\dfrac{1}{2}$

_____________________________________________________________________

$\dfrac{4}{9}$ và $\dfrac{1}{2}$ $\text{(}$ MSC$\text{ :18 )}$

$\dfrac{4}{9}$ = $\dfrac{4 \times 2}{9 \times 2}$ = $\dfrac{8}{18}$ ; $\dfrac{1}{2}$ = $\dfrac{1 \times 9}{2 \times 9}$ = $\dfrac{9}{18}$

Vì $\text{8 < 9}$ nên $\dfrac{4}{9}$ $\text{<}$ $\dfrac{1}{2}$

$\dfrac{4}{9}$ $\text{<}$ $\dfrac{1}{2}$

_____________________________________________________________________

$\dfrac{5}{12}$ và $\dfrac{1}{2}$ $\text{(}$ MSC$\text{ :24 )}$

$\dfrac{5}{12}$ = $\dfrac{5 \times 2}{12 \times 2}$ = $\dfrac{10}{24}$ ; $\dfrac{1}{2}$ = $\dfrac{1 \times 12}{2 \times 12}$ = $\dfrac{12}{24}$

Vì $\text{10 < 12}$ nên $\dfrac{5}{12}$ $\text{<}$ $\dfrac{1}{2}$

$\dfrac{5}{12}$ $\text{<}$ $\dfrac{1}{2}$

_____________________________________________________________________

$\dfrac{7}{17}$ và $\dfrac{1}{2}$ $\text{(}$ MSC$\text{ :34 )}$

$\dfrac{7}{17}$ = $\dfrac{7 \times 2}{17 \times 2}$ = $\dfrac{14}{34}$ ; $\dfrac{1}{2}$ = $\dfrac{1 \times 17}{2 \times 17}$ = $\dfrac{17}{34}$

Vì $\text{14 < 17}$ nên $\dfrac{7}{17}$ $\text{<}$ $\dfrac{1}{2}$

$\dfrac{7}{17}$ $\text{<}$ $\dfrac{1}{2}$

$#minhanh123hellovetnam$