giups mik câu 13 và 12
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
A = { 13; 14; 15 }
B = { 1; 2; 3; 4 }
C = { 13; 14; 15 }
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
6: \(=\dfrac{2^{20}\left(2^{20}-1+3^{20}\right)}{3^{20}\left(2^{20}-1+3^{20}\right)}=\left(\dfrac{2}{3}\right)^{20}\)
7: \(=\dfrac{7}{3}\left(19+\dfrac{1}{3}-33-\dfrac{1}{3}\right)-\dfrac{2}{7}=\dfrac{7}{3}\cdot\left(-14\right)-\dfrac{2}{7}\)
\(=-\dfrac{98}{3}-\dfrac{2}{7}=-\dfrac{692}{21}\)
8: \(=\dfrac{1}{9}-\left(\dfrac{1}{4}:2+\dfrac{7}{21}\cdot\dfrac{4}{16}\right)\)
\(=\dfrac{1}{9}-\dfrac{1}{8}-\dfrac{1}{12}=-\dfrac{7}{72}\)
10: =(-0,5)^2-17/2+0,5
=0,25+0,5-8,5
=-7,75
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Rightarrow3\left|x-\dfrac{21}{10}\right|=5,4\Rightarrow\left|x-\dfrac{21}{10}\right|=\dfrac{9}{5}\)
\(\Rightarrow\left[{}\begin{matrix}x-\dfrac{21}{10}=\dfrac{9}{5}\\x-\dfrac{21}{10}=-\dfrac{9}{5}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{39}{10}\\x=\dfrac{3}{10}\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
d: \(\Leftrightarrow\dfrac{x+14}{86}+1+\dfrac{x+15}{85}+1+\dfrac{x+16}{84}+1+\dfrac{x+17}{83}+1+\dfrac{x+116}{4}-4=0\)
=>x+100=0
hay x=-100
a: \(\Leftrightarrow2\left(x+1\right)^2+3\left(x^2-3x+2\right)=\left(3x-1\right)\left(x-4\right)+56\)
\(\Leftrightarrow2x^2+4x+2+3x^2-9x+6-\left(3x^2-13x+4\right)-56=0\)
\(\Leftrightarrow5x^2-5x-48-3x^2+13x-4=0\)
\(\Leftrightarrow2x^2+8x-52=0\)
\(\Leftrightarrow x^2+4x-13=0\)
\(\Leftrightarrow\left(x+2\right)^2=17\)
hay \(x\in\left\{-\sqrt{17}-2;\sqrt{17}-2\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1) = \(\frac{3}{5}\)
2) =\(\frac{6}{7}\)
3)\(\frac{9}{13}\)
4)\(\frac{4}{13}\)
đi học đc mang đt luôn :o
Oh đt