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![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{3}{8}:\frac{9}{10}=\frac{3}{8}\cdot\frac{10}{9}=\frac{30}{72}=\frac{5}{12}\)
b) \(\frac{4}{9}:\frac{12}{8}=\frac{4}{9}\cdot\frac{8}{12}=\frac{32}{108}=\frac{8}{27}\)
Xin lỗi, bài này mk ko biết tính bằng cách thuận tiện, chỉ biết làm thế này thôi!!
![](https://rs.olm.vn/images/avt/0.png?1311)
a/ \(\frac{3}{8}:\frac{9}{10}=\frac{3}{8}.\frac{10}{9}=\frac{3.5.2}{4.2.3.3}=\frac{5}{12}\)
b/ \(\frac{4}{9}:\frac{12}{8}=\frac{4}{9}.\frac{8}{12}=\frac{2.4.4}{3.3.3.4}=\frac{8}{27}\)
a) 3/8 chia 9/10=3/8x10/9=5/12
b)4/9 chia 12/8=4/9x8/12=8/27
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)
\(=1:\frac{5}{6}\)
\(=1\times\frac{6}{5}\)
\(=\frac{6}{5}\)
\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)
\(=1:\frac{5}{6}\)
\(=1\times\frac{6}{5}\)
\(=\frac{6}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(\frac{2}{3}:\frac{4}{9}+\frac{1}{3}:\frac{4}{9}\)
=\(\frac{4}{9}:\left(\frac{2}{3}+\frac{1}{3}\right)\)
=\(\frac{4}{9}:1=\frac{4}{9}\)
b
![](https://rs.olm.vn/images/avt/0.png?1311)
=\(\frac{3}{4}\times\left(\frac{8}{9}+\frac{2}{3}\right)\)
\(=\frac{3}{4}\times\frac{14}{9}\)
\(=\frac{7}{6}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bạn thử rút gọn các phân số đi
Sau đó bạn đi tính
Như vậy kết quả sẽ nhỏ hơn đấy
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)\)
\(=\frac{5}{5}+\frac{7}{7}=1+1=2\)
a) \(\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)\)
= 1 + 1
= 2
b) \(\frac{4}{9}+\frac{8}{9}+\frac{12}{9}+\frac{16}{9}+...+\frac{48}{9}+\frac{52}{9}+\frac{56}{9}\)
\(=\frac{4+8+12+16+...+48+52+56}{9}\)
Xét 4 + 8 + 12 + 16 + ... + 48 + 52 + 56
Số các số hạng là:
(56 - 4) : 4 + 1 = 14 (số)
4 + 8 + 12 + 16 + ... + 48 + 52 + 56 = (56 + 4) x 14 : 2 = 420
\(\frac{4+8+12+16+...+48+52+56}{9}=\frac{420}{9}=\frac{140}{3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
(\(\frac{1}{2}\):\(\frac{1}{3}\):\(\frac{1}{6}\)) +\(\frac{1}{5}\)
= 9 + \(\frac{1}{5}\)
=\(\frac{46}{5}\)
K minh nhe ban
\(\frac{1}{2}:\frac{1}{5}+\frac{1}{3}:\frac{1}{5}+\frac{1}{6}:\frac{1}{5}\)
\(=\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{6}\right):\frac{1}{5}\)
\(=\left(\frac{3}{6}+\frac{2}{6}+\frac{1}{6}\right):\frac{1}{5}\)
\(=1:\frac{1}{5}\)
\(=1\times5\)
\(=5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\frac{2}{5}+\frac{1}{6}+\frac{3}{5}\)
\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{1}{6}\)
\(=1+\frac{1}{6}\)
\(=\frac{7}{6}\)
Hok tốt!~
\(\frac{5}{6}:\frac{8}{9}-\frac{3}{4}:\frac{8}{9}\)
\(=\left(\frac{5}{6}-\frac{3}{4}\right):\frac{8}{9}\)
\(=\frac{1}{12}:\frac{8}{9}\)
\(=\frac{1}{12}\times\frac{9}{8}\)
\(=\frac{3}{32}\)
(\(\frac{5}{6}\)-\(\frac{3}{4}\)) : \(\frac{8}{9}\)
=\(\frac{1}{12}\): \(\frac{8}{9}\)
=\(\frac{3}{32}\)
k nhé, sau đó kb lun!