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= 13 x 2 x 8 + 4 x 13 - 10 x 2 x 13
= 13 x 16 + 4 x 13 - 20 x 13
= 13 x (16 + 4 - 20)
= 13 x 0
= 0
![](https://rs.olm.vn/images/avt/0.png?1311)
= \(\frac{13}{45}x\left(\frac{15}{26}-1\frac{1}{26}+\frac{11}{26}\right)=\frac{13}{45}x\left(\frac{15}{26}-\frac{27}{26}+\frac{11}{26}\right)=\frac{13}{45}x\left(\frac{27}{26}-\frac{27}{26}\right)=\frac{13}{45}x0=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
26*8+2*2*13-10*26
=26*8+2*26-10*26
=26*(8+2-10)
=26*0
=0
Nhớ tick mik nha
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`@` `\text {Ans}`
`\downarrow`
\(39 \times 123 + 26 \times 47 - 13 \times 163\)
`= 3 \times 13 \times 123 + 2 \times 13 \times 47 - 13 \times 163`
`= 13 \times (3 \times 123 + 2 \times 47 - 163)`
`= 13 \times (369 + 94 - 163)`
`= 13 \times 300`
`=3900`
\(39\times123+26\times47-13\times163\)
\(=13\times\left(3\times123+2\times47-163\right)\)
\(=13\times300\)
\(=3900\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{22\cdot13\cdot17}{55\cdot26\cdot51}\)
\(=\frac{22\cdot13\cdot17}{55\cdot13\cdot2\cdot3\cdot17}\)
\(=\frac{11\cdot2}{55\cdot2\cdot3}\)
\(=\frac{11}{55\cdot3}=\frac{11}{165}\)
\(\frac{22.13.17}{55.26.51}\) = \(\frac{2.11.13.17}{11.5.13.2.17.3}\) = \(\frac{1}{15}\)
. là dấu nhân nhé
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\(\dfrac{5}{13}\) \(\times\) \(\dfrac{9}{14}\) \(\times\) \(\dfrac{28}{27}\) \(\times\) \(\dfrac{26}{35}\)
= \(\dfrac{5}{13}\) \(\times\) \(\dfrac{9}{14}\) \(\times\) \(\dfrac{14\times2}{9\times3}\) \(\times\) \(\dfrac{13\times2}{5\times7}\)
= \(\dfrac{5\times9\times14\times13}{5\times9\times14\times13}\) \(\times\) \(\dfrac{2\times2}{3\times7}\)
= 1 \(\times\) \(\dfrac{4}{21}\)
= \(\dfrac{4}{21}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a/ \(x\left(x+7\right)=0\) \(\Rightarrow\left[\begin{matrix}x=0\\x+7=0\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}x=0\\x=-7\end{matrix}\right.\)
b/ \(\left(-x+5\right)\left(3-x\right)=0\) \(\Rightarrow\left[\begin{matrix}-x+5=0\\3-x=0\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}x=5\\x=3\end{matrix}\right.\)
c/ \(\left|x-1\right|=3\) \(\Rightarrow\left[\begin{matrix}x-1=3\\1-x=3\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}x=4\\x=-2\end{matrix}\right.\)
d/ \(-13\left|x\right|=-26\) \(\Rightarrow\left|x\right|=2\) \(\Rightarrow x=\pm2\)
e/ \(x.x-8=-2.\left(-13\right)-\left(-2\right)\)
\(\Rightarrow x^2=36\) \(\Rightarrow\left|x\right|=6\) \(\Rightarrow x=\pm6\)
\(x-\left(13-x\right)=x-26\)
\(x-13+x=x-26\)
\(x+x-x=-26+13\)
\(x=-13\)
Vậy \(x=-13\)
\(x-\left(13-x\right)=x-26\)
\(\Leftrightarrow x-13+x=x-26\)
\(\Leftrightarrow x=-26+13=-13\)