Đáp án:

 

Giải thích các bước giải:

 Bài 1:a:25/36.  B:5/8 c:1/2 d:26/37 

bài2:5/7, 7/19 b 26/24=13/12 11/22=1/2  21/36=7/12

1.

a, $\dfrac{50}{72}$ = $\dfrac{50 : 2}{72 : 2}$ = $\dfrac{25}{36}$

b, $\dfrac{25}{40}$ = $\dfrac{25 : 5}{40 : 5}$ = $\dfrac{5}{8}$

c, $\dfrac{12}{24}$ = $\dfrac{12 : 12}{24 : 12}$ = $\dfrac{1}{2}$

d, $\dfrac{52}{74}$ = $\dfrac{52 : 2}{74 : 2}$ = $\dfrac{26}{37}$

2.

a, Phân số tối giản : $\dfrac{5}{9}$ ; $\dfrac{7}{19}$

b, Phân số chưa tối giản : $\dfrac{26}{24}$ ; $\dfrac{11}{22}$ ; $\dfrac{21}{36}$

Rút gọn : $\dfrac{26}{24}$ = $\dfrac{26 : 2}{24 : 2}$ = $\dfrac{13}{12}$

                $\dfrac{11}{22}$ = $\dfrac{11 : 11}{22 : 11}$ = $\dfrac{1}{2}$

                $\dfrac{21}{36}$ = $\dfrac{21 : 3}{36 : 3}$ = $\dfrac{7}{12}$

3.

$\dfrac{36}{54}$ = $\dfrac{36 : 18}{54 : 18}$ = $\dfrac{2}{3}$

$\dfrac{65}{40}$ = $\dfrac{65 : 5}{40 : 5}$ = $\dfrac{13}{8}$

$\dfrac{9}{81}$ = $\dfrac{9 : 9}{81 : 9}$ = $\dfrac{1}{9}$

$\dfrac{22}{76}$ = $\dfrac{22 : 2}{76 : 2}$ = $\dfrac{11}{38}$

$\dfrac{30}{54}$ = $\dfrac{30 : 6}{54 : 6}$ = $\dfrac{5}{9}$

$\text{Xin hay nhất cho nhóm}$