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\(\frac{1}{3}x+\frac{2}{5}\left(x-1\right)=0\)
\(\Leftrightarrow\frac{1}{3}x+\frac{2}{5}x-\frac{2}{5}=0\)
\(\Leftrightarrow\frac{11}{15}x=\frac{2}{5}\)
\(\Leftrightarrow x=\frac{2}{5}\div\frac{11}{15}=\frac{2.15}{5.11}=\frac{6}{11}\)
Vậy x = 6/11
a) \(\frac{1}{3}.x+\frac{2}{5}.\left(x-1\right)=0\)
\(\frac{1}{3}.x+\frac{2}{5}.x-\frac{2}{5}=0\)
\(x.\left(\frac{1}{3}+\frac{2}{5}\right)-\frac{2}{5}=0\)
\(x.\frac{11}{15}-\frac{2}{5}=0\)
\(x.\frac{11}{15}=\frac{2}{5}\)
\(x=\frac{2}{5}:\frac{11}{15}\)
\(x=\frac{6}{11}\)
b) \(3.\left(x-\frac{1}{2}\right)-5.\left(x+\frac{3}{5}\right)=x+\frac{1}{5}\)
\(3x-\frac{3}{2}-5x-3=x+\frac{1}{5}\)
\(3x-5x-\left(\frac{3}{2}+3\right)=x+\frac{1}{5}\)
\(-2x-\frac{9}{2}=x+\frac{1}{5}\)
\(\Rightarrow-2x-x=\frac{1}{5}+\frac{9}{2}\)
\(-3x=\frac{47}{10}\)
\(x=\frac{47}{10}:\left(-3\right)\)
\(x=\frac{-47}{30}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
=> \(\left(3x-\frac{3}{2}\right)-\left(5x-3\right)=-x+\frac{1}{5}
\)
=> \(3x-\frac{3}{2}-5x+3=-x+\frac{1}{5}\)
=> \(3x-5x-\frac{3}{2}+3=-x+\frac{1}{5}\)
=> \(-2x-\left(\frac{3}{2}-3\right)=-x+\frac{1}{5}\)
=> \(-2x-\frac{-3}{2}=-x+\frac{1}{5}\)
=> \(-2x+\frac{3}{2}=-x+\frac{1}{5}\)
=> \(-2x+x=\frac{1}{5}-\frac{3}{2}\)(Chuyển vế)
=> \(x.\left(-2+1\right)=\frac{-13}{10}\)
=> \(x.\left(-1\right)=\frac{-13}{10}\)
=> \(x=\frac{-13}{10}:\left(-1\right)\)
=> \(x=\frac{13}{10}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(3\left(2x-\frac{5}{4}\right)=\left(3-1\frac{1}{2}\right)\left(x-\frac{1}{2}\right)\)
\(\Leftrightarrow6x-\frac{15}{4}=\frac{3}{2}x+\frac{1}{12}\)
\(\Leftrightarrow\frac{9}{2}x+\frac{3}{4}=\frac{15}{4}\)
\(\Leftrightarrow\frac{9}{2}x=3\)
\(\Leftrightarrow x=\frac{2}{3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\frac{3}{4}.x-\frac{9}{16}\right).\left(\frac{1}{3}+\frac{-3}{5}:x\right)=0\)
<=> \(\hept{\begin{cases}\frac{3}{4}.x-\frac{9}{16}=0\\\frac{1}{3}-\frac{3}{5}.\frac{1}{x}=0\end{cases}}\)
<=> \(\hept{\begin{cases}x=\frac{3}{4}\\\frac{3}{5x}=\frac{1}{3}\end{cases}}\)
<=> \(\hept{\begin{cases}x=\frac{3}{4}\\x=\frac{9}{5}\end{cases}}\)
\(\left(x-\frac{1}{3}\right)\left(\frac{2}{5}+x\right)>0\)
<=> \(\hept{\begin{cases}x-\frac{1}{3}>0\\x+\frac{2}{5}>0\end{cases}}\)hoặc \(\hept{\begin{cases}x-\frac{1}{3}< 0\\x+\frac{2}{5}< 0\end{cases}}\)
<=> \(\hept{\begin{cases}x>\frac{1}{3}\\x>\frac{-2}{5}\end{cases}}\)hoặc \(\hept{\begin{cases}x< \frac{1}{3}\\x< \frac{-2}{5}\end{cases}}\)
<=>\(x>\frac{1}{3}\)hoặc \(x< \frac{-2}{5}\)
câu c tương tự nha
học tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
Tìm x, biết:
3(x+2)(x+5) +5(x+5)(x+10) +7(x+10)(x+17) =x(x+2)(x+17) (x∉−2;−5;−10;−17)
2(x−1)(x−3) +5(x−3)(x−8) +12(x−8)(x−20) −1x−20 =−34 (x∉1;3;8;20)
x+110 +2+111 x+112 =x+113 +x+114
x−1030 +x−1443 +x−595 +x−1488 =0
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (2x+3)-(5x-17)=9
2x+3-5x+17=9
-3x+20=9
-3x=9-20=-11
=>x=11/3
b) \(\left(\frac{1}{5}+\frac{4}{5}x\right)-\left(\frac{2}{5}x+\frac{1}{9}\right)=\frac{3}{7}\)
=> \(\frac{1}{5}+\frac{4}{5}x-\frac{2}{5}x-\frac{1}{9}=\frac{3}{7}\)
=> \(\left(\frac{1}{5}-\frac{1}{9}\right)+\left(\frac{4}{5}x-\frac{2}{5}x\right)=\frac{3}{7}\)
\(\frac{4}{45}+\frac{2}{5}x=\frac{3}{7}\)
\(\frac{2}{5}x=\frac{3}{7}-\frac{4}{45}=\frac{107}{315}\)
x=107/315:2/5=107/126
![](https://rs.olm.vn/images/avt/0.png?1311)
\(3.\left(x-\frac{1}{2}\right)-5.\left(x+\frac{3}{5}\right)=-x+\frac{1}{5}\)
\(3x-\frac{3}{2}-\left(5x+3\right)=\left(-x\right)+\frac{1}{5}\)(t/c phân phối của phép nhân đối với phép cộng)
\(3x-\frac{3}{2}-5x-3=\left(-x\right)+\frac{1}{5}\)(qui tắc bỏ dấu ngoặc)
\(3x-5x+x=\frac{1}{5}+3+\frac{3}{2}\)(qui tắc chuyển vế)
\(\left(3-5+1\right)x=\frac{47}{10}\)
\(-x=4,7\)
\(x=-4,7\)
\(\frac{\left(0,35+0,43\right)x}{5}=1\Rightarrow\left(0,35+0,43\right)x=1.5=5\Rightarrow x=\frac{5}{0,35+0,43}=\frac{250}{39}\)