![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{3}{7}x-\frac{1}{35}=\frac{3}{5}\)
\(\frac{3}{7}x=\frac{3}{5}+\frac{1}{35}\)
\(\frac{3}{7}x=\frac{22}{35}\)
\(x=\frac{49}{35}=1,4\)
b) \(1,5-x:\frac{1}{2}=\frac{1}{4}\)
\(x:\frac{1}{2}=1,5-\frac{1}{4}\)
\(x:\frac{1}{2}=\frac{5}{4}\)
\(x=\frac{5}{4}.\frac{1}{2}\)
\(x=\frac{5}{8}\)
Vậy ..
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
\(\frac{4}{12}+\frac{4}{20}+\frac{4}{30}+...+\frac{4}{306}\)
\(=4\cdot\left(\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{306}\right)\)
\(=4\cdot\left(\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+...+\frac{1}{17\cdot18}\right)\)
\(=4\cdot\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{17}-\frac{1}{18}\right)\)
\(=4\cdot\left(\frac{1}{3}-\frac{1}{18}\right)\)
\(=4\cdot\left(\frac{6}{18}-\frac{1}{18}\right)\)
\(=4\cdot\frac{5}{18}\)
\(=\frac{10}{9}\)
Bài 2 :
\(\left(3x-4\right)-\left(6x+7\right)=8\)
\(3x-4-6x-7=8\)
\(\left(3x-6x\right)-\left(4+7\right)=8\)
\(-3x-11=8\)
\(-3x=8+11\)
\(-3x=19\)
\(x=19:\left(-3\right)\)
\(x=\frac{-19}{3}\)
Vậy \(x=\frac{-19}{3}\)
b ) \(\left(\frac{4}{5}x+3\right):\left(-4\right)=\frac{1}{2}\)
\(\frac{4}{5}x+3=\frac{1}{2}\cdot\left(-4\right)\)
\(\frac{4}{5}x+3=-2\)
\(\frac{4}{5}x=\left(-2\right)-3\)
\(\frac{4}{5}x=-5\)
\(x=\left(-5\right):\frac{4}{5}\)
\(x=\left(-5\right)\cdot\frac{4}{5}\)
\(x=-4\)
Vậy \(x=-4\)
k nha !
\(\frac{4}{12}\)+\(\frac{4}{20}\)+...+\(\frac{4}{306}\)=\(\frac{4}{3.4}\)+\(\frac{4}{4.5}\)+...+\(\frac{4}{17.18}\)=4(\(\frac{1}{3}\)-\(\frac{1}{4}\)+\(\frac{1}{4}\)-\(\frac{1}{5}\)+...+\(\frac{1}{17}\)-\(\frac{1}{18}\))
=4(\(\frac{1}{3}\)-\(\frac{1}{8}\))=4.\(\frac{5}{24}\)=\(\frac{5}{6}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : 3x - 7/3 - 2x - 1/2 = 7 .
=> x ( 3 - 2 ) - ( 7/3 + 1/2 ) = 7 .
=> x - ( 14/6 + 3/6 ) = 7 .
=> x - 17/6 = 7 .
=> x = 7 + 17/6 .
=> x = 59/6 .
vậy x = 59/6 .
\(3x-\frac{7}{3}-2x-\frac{1}{2}=7\)
\(\Leftrightarrow\left(3x-2x\right)-\left(\frac{7}{3}+\frac{1}{2}\right)=7\)
\(\Leftrightarrow x-\frac{17}{6}=7\)
\(\Leftrightarrow x=7+\frac{17}{6}\)
\(\Leftrightarrow x=\frac{59}{6}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1.
| x + 2 | = | 2 - 3x |
xét 2 trường hợp :
+) TH1 :
2 - 3x = x + 2
-3x + x = 2 + 2
2x = 4
x = 4 : 2 = 2
+) TH2 :
2 - 3x = - ( x + 2 )
2 - 3x = -x - 2
-3x - x = 2 - 2
-4x = 0
x = 0 : ( -4 )
x = 0
bài còn lại tương tự
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\text{2^5.3 - 3.(x+1)=42}\)
\(3\left(x+1\right)=54\)
\(x+1=18\)
\(x=17\)
\(\text{(4x + 5) : 3 - 11^2:11=2^2}\)
\((4x+5):3-11=4\)
\((4x+5):3=15\)
\((4x+5)=5\)
\(4x=0\)
\(x=0\)
\(\text{3x - 15 . 4 = 6.(19 - x)}\)
\(\text{3x - 60 = 6.(19 - x)}\)
\(\text{3x - 60 :(19-x)= 6}\)
\(\Rightarrow x=6\)
\(\text{(x - 7).(2x - 16)=0}\)
\(\Rightarrow\hept{\begin{cases}x-7=0\\2x-16=0\end{cases}\Rightarrow\hept{\begin{cases}x=7\\8\end{cases}}}\)