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Nay rảnh lại qua làm mấy bài lớp 4 ^^
Tui làm luôn kh ghi đề nhá
1,
\(\frac{2}{3}+\frac{8}{15}=\frac{6}{5}\)
\(\frac{2}{5}+\frac{2}{3}=\frac{16}{15}\)
\(\frac{2}{3}+\frac{5}{6}=\frac{3}{2}\)
2,
\(\cdot\frac{3}{7}+\frac{6}{5}+\frac{4}{7}\)
\(=\frac{3}{7}+\frac{4}{7}+\frac{6}{5}\)
\(=1+\frac{6}{5}\)
\(=\frac{11}{5}\)
\(\cdot\frac{6}{4}+\frac{7}{3}+\frac{4}{4}+\frac{3}{3}\)
\(=\frac{6}{4}+\frac{4}{4}+\frac{7}{3}+\frac{3}{3}\)
\(=\frac{10}{4}+\frac{10}{3}\)
\(=\frac{35}{6}\)
23+815=6523+815=65
25+23=161525+23=1615
23+56=3223+56=32
2,
⋅37+65+47⋅37+65+47
=37+47+65=37+47+65
=1+65=1+65
=115=115
⋅64+73+44+33⋅64+73+44+33
=64+44+73+33=64+44+73+33
=104+103=104+103
=356
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\frac{42}{25}:\frac{y}{5}=\frac{6}{5}\)
\(\frac{y}{5}=\frac{42}{25}:\frac{6}{5}\)
\(\frac{y}{5}=\frac{42}{25}\times\frac{5}{6}\)
\(\frac{y}{5}=\frac{7}{5}\)
\(\Leftrightarrow5y=7.5\)
\(5y=35\)
\(y=7\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 5/6=35/42 ; 14/21=28/42 ; 8/7=48/42 ; 15/14=45/42
Sắp xếp các số theo thứ tự từ bé đến lớn ta được: 28/42 , 35/42 , 45/42 , 48/42 , 51/42
Vậy ta có 14/21,5/6,15/14,8/7,51/42
b) 8/9,7/8,6/7,5/6,4/5,1/2
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 14/21; 5/6 ; 15/14 ; 8/7 ; 51/42
b) 8/9 ; 7/8 ; 6/7 ; 5/6 ; 4/5 ; 1/2
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
Rút gọn các phân số sau:
\(\dfrac{12}{24}\) = \(\dfrac{12:12}{24:12}\) = \(\dfrac{1}{2}\)
\(\dfrac{120}{90}\) = \(\dfrac{120:30}{90:30}\) = \(\dfrac{4}{3}\)
\(\dfrac{42}{24}\) = \(\dfrac{42:6}{24:6}\) = \(\dfrac{7}{4}\)
Bài 2:
Tính bằng cách thuận tiện:
\(\dfrac{13}{19}\) + \(\dfrac{18}{19}\) + \(\dfrac{17}{19}\)
= \(\dfrac{13+18+17}{19}\)
= \(\dfrac{\left(13+17\right)+18}{19}\)
= \(\dfrac{48}{19}\)
\(\dfrac{12}{17}\) + \(\dfrac{19}{17}\) + \(\dfrac{8}{17}\)
= \(\dfrac{12+19+8}{17}\)
= \(\dfrac{\left(12+8\right)+19}{17}\)
= \(\dfrac{39}{17}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
4/7 = 16/28
36/42 = 6/7
5/8 = 25/40 = 30/48
25/15 = 5/3 = 10/6
kick mình nha
35/21
TINH MA