Ta có: \(A=\frac{432143214321}{999999999999}=\frac{4321\times100010001}{9999\times100010001}=\frac{4321}{9999}< \frac{1}{2}\)

\(B=\frac{1212+1212+1212+1212}{1919+1919+1919+1919}=\frac{1212\times4}{1919\times4}=\frac{1212}{1919}=\frac{12\times101}{19\times101}=\frac{12}{19}>\frac{1}{2}\)

Do:\(A< \frac{1}{2}< B\Rightarrow A< B\)

\(\frac{1717}{1919}.\frac{303}{1818}+\frac{1717}{1919}.\frac{1515}{1818}\)

\(=\frac{1717}{1919}.\left(\frac{303}{1818}+\frac{1515}{1818}\right)\)

\(=\frac{1717}{1919}.1\)

\(=\frac{17}{19}\)

Dấu "." là dấu " x " 

học tốt!!!

\(A=\frac{17\cdot101}{19\cdot101}\cdot\frac{1\cdot303}{6\cdot303}+\frac{17\cdot101}{19\cdot101}\cdot\frac{5\cdot303}{6\cdot303}\) 

\(=\frac{17}{19}\cdot\frac{1}{6}+\frac{17}{19}\cdot\frac{5}{6}\) 

\(=\frac{17}{19}\cdot\left(\frac{5}{6}+\frac{1}{6}\right)\) 

\(=\frac{17}{19}\cdot1\) 

\(=\frac{17}{19}\)

Bài 1:

a) Ta có: (-181)-(-219)-819+281

=-181+219-819+281

=100-600

=-500

b) Ta có: [1919-(216+1919)]+1216

=1919-216-1919+1216

=1000

a; \(\dfrac{1919}{2121}\) = \(\dfrac{1919:101}{2121:101}\) = \(\dfrac{19}{21}\)

b; 17 x 5 - \(\dfrac{17}{120}\) - 103

= 85 - \(\dfrac{17}{120}\) - 103

= \(\dfrac{10200}{120}\) - \(\dfrac{17}{120}\) - \(\dfrac{12360}{120}\)

= \(\dfrac{10183}{120}\) - \(\dfrac{12360}{120}\)

= \(\dfrac{-2177}{120}\)

c; 2929 - \(\dfrac{101}{2\times1919}\) + 404

= 2929 - \(\dfrac{1}{38}\) + 404

= \(\dfrac{111302}{38}\) - \(\dfrac{1}{38}\) + \(\dfrac{15352}{38}\)

= \(\dfrac{111301}{38}\) + \(\dfrac{15352}{38}\)

 = \(\dfrac{126653}{38}\)

19/37

=\(\frac{19}{12}\)+ \(\frac{51}{36}\)

= 3

1919/1212 + 51515151/36363636 = 3.

Ai tk cho mình mình tk lại.

bằng 3 nhé

=19/12+17/12=3

1.2929-101=2828

2.1919+101=2020

OK

\(\frac{2929-101}{1919+101}=\frac{2828}{2020}=\frac{7}{5}=1,4\)

\(2929-\frac{101}{1919}+101=3029,947368\)

Nhớ click cho mik nha !!!!!!!!!!!!!!