Rút gọn rồi tính 2 3 - 3 9
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
$\frac{1}{2}+\frac{1}{2}=\frac{1+1}{2}=\frac{2}{2}=1$
$\frac{3}{8}+\frac{1}{8}=\frac{3+1}{8}=\frac{4}{8}=\frac{1}{2}$
$\frac{7}{9}+\frac{5}{9}=\frac{7+5}{9}=\frac{12}{9}=\frac{3\times 4}{3\times 3}=\frac{4}{3}$
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
TL
\(\frac{2}{3}-\frac{3}{9}=\frac{2}{3}-\frac{1}{3}=\frac{1}{3}\)
\(\frac{7}{5}-\frac{15}{25}=\frac{7}{5}-\frac{3}{5}=\frac{4}{5}\)
\(\frac{3}{2}-\frac{4}{8}=\frac{3}{2}-\frac{1}{2}=\frac{2}{2}\)
nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
A) \(\dfrac{5}{10}-\dfrac{2}{15}\)
\(=\dfrac{1}{2}-\dfrac{2}{15}\)
\(=\dfrac{15}{30}-\dfrac{4}{30}\)
\(=\dfrac{11}{30}\)
B)\(\dfrac{5}{20}-\dfrac{1}{6}\)
\(=\dfrac{1}{4}-\dfrac{1}{6}\)
\(=\dfrac{6}{24}-\dfrac{4}{24}\)
\(=\dfrac{2}{24}=\dfrac{1}{12}\)
C) \(\dfrac{6}{18}-\dfrac{6}{24}\)
\(=\dfrac{1}{3}-\dfrac{1}{4}\)
\(=\dfrac{4}{12}-\dfrac{3}{12}\)
\(=\dfrac{1}{12}\)
D) \(\dfrac{5}{9}-\dfrac{3}{12}\)
\(=\dfrac{5}{9}-\dfrac{1}{4}\)
\(=\dfrac{20}{36}-\dfrac{9}{36}\)
\(=\dfrac{11}{36}\).
a: =1/2-2/15
=15/30-4/30
=11/30
b: =1/4-1/6
=3/12-2/12
=1/12
c: =1/3-1/4
=1/12
d: =20/36-9/36
=11/36
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\frac{2^{15}\cdot\left(3^2\right)^4}{2^7\cdot3^7\cdot\left(2^3\right)^3}\)
\(=\frac{2^{15}\cdot3^8}{2^7\cdot3^7\cdot2^9}\)
\(=\frac{2^{15}\cdot3^8}{2^{16}\cdot3^7}\)
\(=\frac{3}{2}\)
Bài làm :
\(\frac{2^{15}.9^4}{6^7.8^3}\)
\(=\frac{2^{15}.\left(3^2\right)^4}{\left(2.3\right)^7.(2^3)^3}\)
\(=\frac{2^{15}.3^8}{2^7.3^7.2^9}\)
\(=\frac{3}{2}\)
Học tốt nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài làm :
Ta có :
\(\frac{2^{15}.9^4}{6^7.8^3}=\frac{2^{15}.\left(3^2\right)^4}{\left(2.3\right)^7.\left(2^3\right)^3}=\frac{2^{15}.3^8}{2^7.3^72^9}=\frac{3}{2}\)
Bài làm :
\(\frac{2^{15}.9^4}{6^7.8^3}\)
\(=\frac{2^{15}.\left(3^2\right)^4}{\left(2.3\right)^7.\left(2^3\right)^3}\)
\(=\frac{2^{15}.3^8}{2^7.3^7.2^9}\)
\(=\frac{3}{2}\)
Học tốt nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{3}{12}+\dfrac{1}{4}=\dfrac{3:3}{12:3}+\dfrac{1}{4}=\dfrac{1}{4}+\dfrac{1}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)
\(\dfrac{4}{10}+\dfrac{3}{5}=\dfrac{4:2}{10:2}+\dfrac{3}{5}=\dfrac{2}{5}+\dfrac{3}{5}=\dfrac{5}{5}=1\)
\(\dfrac{12}{27}+\dfrac{2}{9}=\dfrac{12:3}{27:3}+\dfrac{2}{9}=\dfrac{4}{9}+\dfrac{2}{9}=\dfrac{6}{9}=\dfrac{2}{3}\)
\(\dfrac{7}{3}+\dfrac{20}{15}=\dfrac{7}{3}+\dfrac{20:5}{15:5}=\dfrac{7}{3}+\dfrac{4}{3}=\dfrac{11}{3}\)
2 3 - 3 9 = 2 3 - 1 3 = 1 3