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![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=26+28+29+30+31+32+33\)
\(=\left(27+33\right)+\left(28+32\right)+\left(29+31\right)+26+30\)
\(=60+60+60+30+26\)
\(=236\)
A = 26 + 27 + 28 + 29 + 30 + 31 + 32 + 33
A = ( 26 + 30 ) + ( 33 + 27 ) + ( 28 + 32 ) + ( 29 + 31 )
A = 56 + 60 + 60 + 60
A = 236
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\(\frac{121212}{161616}-\left(\frac{151515}{323232}-x\right)=2\)
=> \(\frac{3}{4}-\left(\frac{15}{32}-x\right)=2\)
=> \(\frac{15}{32}-x=\frac{3}{4}-2\)
=> \(\frac{15}{32}-x=-\frac{5}{4}\)
=> \(x=\frac{15}{32}-\frac{-5}{4}=\frac{15}{32}+\frac{5}{4}=\frac{55}{32}\)
b) \(\frac{x}{2}+\frac{x}{6}+\frac{x}{12}+\frac{x}{20}+\frac{x}{30}+\frac{x}{42}+\frac{x}{56}+\frac{x}{72}+\frac{x}{90}=\frac{9}{5}\)
=> \(\frac{x}{1\cdot2}+\frac{x}{2\cdot3}+\frac{x}{3\cdot4}+\frac{x}{4\cdot5}+\frac{x}{5\cdot6}+\frac{x}{6\cdot7}+\frac{x}{7\cdot8}+\frac{x}{8\cdot9}+\frac{x}{9\cdot10}=\frac{9}{5}\)
=> \(\frac{x}{1}-\frac{x}{2}+\frac{x}{2}-\frac{x}{3}+...+\frac{x}{9}-\frac{x}{10}=\frac{9}{5}\)
=> \(\frac{x}{1}-\frac{x}{10}=\frac{9}{5}\)
=> \(\frac{10x-x}{10}=\frac{9}{5}\)
=> \(\frac{9x}{10}=\frac{9}{5}\)
=> \(\frac{9x}{10}=\frac{9\cdot2}{5\cdot2}=\frac{18}{10}\)
=> x = 2
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1 poverty
2 decision
3 worried
4 awake
5 singers
7 northen
8 disappeared
9 difference
10 unimportant
11 windy
12 portable
13 sensibly
14 painting
15 mainly
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Để \(B\in Z\Rightarrow5n+8⋮6n+7\)
\(\Rightarrow6.\left(5n+8\right)⋮6n+7\)
\(\Rightarrow30n+48⋮6n+7\)
\(\Rightarrow5.\left(6n+7\right)+13⋮6n+7\)
\(\Rightarrow13⋮6n+7\Rightarrow6n+7\inƯ\left(13\right)=\pm1;\pm13\)
b,GỌI Ư CLN\(\left(5n+8;6n+7\right)=d\)
\(\Rightarrow\)\(\hept{\begin{cases}5n+8⋮d\Rightarrow6.\left(5n+8\right)⋮d\Rightarrow30n+48⋮d\\6n+7⋮d\Rightarrow5.\left(6n+7\right)⋮d\Rightarrow30n+35⋮d\end{cases}}\)
\(\Rightarrow\left(30n+48\right)-\left(30n+35\right)⋮d\)
\(\Rightarrow13⋮d\Rightarrow d=1;-1;13;-13\)
\(+d=13\Rightarrow6n+7⋮13\Rightarrow2.\left(6n+7\right)⋮13\)
\(\Rightarrow12n+14⋮13\)
\(\Rightarrow\left(12n+n\right)+\left(14-n\right)⋮13\)
\(\Rightarrow13n+\left(14-n\right)⋮13\)
\(\Rightarrow14-n=13k\)
\(\Rightarrow n=14-13k\)
Vậy \(n=14-13k\)thì B rút gọn đc
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
B bạn nhé