17⋮x; 21⋮x và 51⋮x
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![](https://rs.olm.vn/images/avt/0.png?1311)
Ta thấy 17+17+.....+17 100 số có chữ số tận cùng là 0
13+13+.....+13 100 số 13 có chữ số tận cùng là 0
Vầy A-B.....
k nha
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+\frac{11}{17}+x+\frac{2}{17}+x+\frac{4}{17}=4x\)
\(\Rightarrow3x+1=4x\)
\(\Rightarrow x=1\)
Vì vế trái >=0 => vế phải >=0 => x>=0
Khi đó ta có: \(x+\frac{11}{17}+x+\frac{2}{17}+x+\frac{4}{17}=4x\)
=> \(3x+1=4x\)
=> \(x=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
9/17.x+268/17.x-345/17.x=16
(9/17+268/17-345/17).x=16
-4.x=16
x=16:-4
x=-4
\(\dfrac{9}{17}x+15\dfrac{13}{17}x-20\dfrac{5}{17}x=16\)
\(\left(\dfrac{9}{17}+15\dfrac{13}{17}-20\dfrac{5}{17}\right)x=16\)
\(\left(\dfrac{9}{17}+\dfrac{268}{17}-\dfrac{345}{17}\right)x=16\)
\(x=16:\left(\dfrac{9}{17}+\dfrac{268}{17}-\dfrac{345}{17}\right)\)
\(x=-4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,0,5x-\frac{2}{3}x=\frac{7}{12}\Rightarrow\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\Rightarrow x\left(\frac{1}{2}-\frac{2}{3}\right)=\frac{7}{12}\Rightarrow x\cdot\left(\frac{3}{6}-\frac{4}{6}\right)=\frac{7}{12}\)
\(\Rightarrow x\cdot\left(-1\right)=\frac{7}{12}\Rightarrow x=\frac{7}{12}:\left(-1\right)=\frac{7}{-12}\)
\(c,\frac{\left(x-5\right)}{12}\cdot\frac{9}{29}=\frac{-6}{29}\Rightarrow\frac{\left(x-5\right)}{12}=\frac{-6}{29}:\frac{9}{26}\)
\(\frac{\Rightarrow\left(x-5\right)}{12}=\frac{-6}{9}=\frac{-2}{3}\Rightarrow x-5=-\frac{2}{3}\cdot12\)
\(\Rightarrow x-5=\frac{-24}{3}=-8\Rightarrow x=-8+5=-3\)
\(a,0,5x-\frac{2}{3}x=\frac{7}{12}\)
\(\Rightarrow\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\Rightarrow-\frac{1}{6}x=\frac{7}{12}\)
\(\Rightarrow x=-\frac{7}{2}\)
\(c,\frac{x-5}{12}\cdot\frac{9}{29}=-\frac{6}{29}\)
\(\Rightarrow\frac{x-5}{12}=-\frac{2}{3}\)
\(\Rightarrow x-5=12.\left(-\frac{2}{3}\right)\)
\(\Rightarrow x-5=-8\)
\(\Rightarrow x=-3\)
![](https://rs.olm.vn/images/avt/0.png?1311)
17⋮x; 21⋮x và 51⋮x \(\Rightarrow\) x \(\in\) ƯC(17,21,51)
Vì 17 là SNtố \(\Rightarrow\) ƯCLN(17,21,51) = 1
\(\Rightarrow\) x \(\in\) Ư(1) = {1; -1}
Giải:
\(\left[{}\begin{matrix}17⋮x\\21⋮x\\51⋮x\end{matrix}\right.\) \(\Rightarrow x\inƯC\left(17;21;51\right)\)
\(17=17\)
\(21=3.7\)
\(51=3.17\)
\(\RightarrowƯCLN\left(17;21;51\right)=1\)
\(\RightarrowƯC\left(17;21;51\right)=Ư\left(1\right)=\left\{\pm1\right\}\)
\(\Rightarrow x\in\left\{\pm1\right\}\)