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tính trừ bt nha bạn vế thương thì cũng tĩnh ra xong mới tính nha
a, \(x\) + \(\dfrac{1}{4}\) - \(\dfrac{3}{8}\) = \(\dfrac{7}{12}\)
\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{7}{12}\)
\(x\) = \(\dfrac{7}{12}\) + \(\dfrac{1}{8}\)
\(x\) = \(\dfrac{17}{24}\)
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\(\left(\frac{5}{10\cdot12}\right)+\left(\frac{5}{12\cdot14}\right)+...+\left(\frac{5}{146\cdot148}\right)\)
\(=5\left[\frac{1}{10\cdot12}+\frac{1}{12\cdot14}+...+\frac{1}{146\cdot148}\right]\)
\(=5\left[\frac{1}{10}-\frac{1}{12}+\frac{1}{12}-\frac{1}{4}+...+\frac{1}{146}-\frac{1}{148}\right]\)
\(=5\left[\frac{1}{10}-\frac{1}{148}\right]\)
\(=5\cdot\frac{69}{740}\)
\(=\frac{69}{148}\)
Không chắc nhá (:
@Trần Nhật Quỳnh@ lag
\(\frac{5}{10\cdot12}+\frac{5}{12\cdot14}+...+\frac{5}{146\cdot148}\)
\(=\frac{5}{2}\left(\frac{2}{10\cdot12}+\frac{2}{12\cdot14}+....+\frac{2}{146\cdot148}\right)\)
\(=\frac{5}{2}\left(\frac{1}{10}-\frac{1}{12}+\frac{1}{12}-\frac{1}{14}+...+\frac{1}{146}-\frac{1}{148}\right)\)
\(=\frac{5}{2}\left(\frac{1}{10}-\frac{1}{148}\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
4 + x = 7 - 2x
4 + x + 2x = 7
4 + 3x = 7
3x = 7 - 4
3x = 3
x = 3 : 3
x =1
5 + x = 8,3 + 4,7 - x
5 + x + x = 8,3 + 4,7
5 + 2x = 13
2x = 13 - 5
2x = 8
x = 8 : 2
x= 4