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`-5,2 + 3,5 . (-5) - 6,9 : 3 + (0,2)^2`
`= -5,2 + (-17,5) - 2,3 + 0,04`
`= -22,7 - 2,3 + 0,04`
`= -25 + 0,04`
`= -24,96`
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
3600/[(5x+335)/x]=50
(5x+355)/x=3600/50
5x+355=72x
72x-5x=355
67x=355
x=355/67
ta có 3600 : [(5x+335) : x] = 50
<=>3600*\(\frac{x}{5x+335}\)= 50
áp dụng quy tắc chéo
<=>3600*x =50* (5x+335)
<=>3600x = 250x +16750
<=>3600x-250x =16750
<=>3350x = 16750
<=> x =5
Ai giúp mình câu này với
(1+1/2+1/3+...+1/2012+1/2013) .x +2013 = 2014+2015/2+...+4025/2012+4026/2013
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=> xy-x+2y-2=5-2(trừ cả 2 vế cho 2 bn nhé)
=> y(x+2)-(x+2)=3
=> (x+2)(y-1)=3
=>\(\hept{\begin{cases}x+2=1\\y-1=3\end{cases}}\)=>\(\orbr{\begin{cases}x=-2\\y=4\end{cases}}\)
\(\hept{\begin{cases}x+2=3\\y-1=1\end{cases}}\)=>\(\hept{\begin{cases}x=1\\y=2\end{cases}}\)
\(\orbr{\begin{cases}x+2=-1\\y-1=-3\end{cases}}\)=> \(\hept{\begin{cases}x=-3\\y=-2\end{cases}}\)
\(\hept{\begin{cases}x+2=-3\\y-1=-1\end{cases}}\)=>\(\hept{\begin{cases}x=-5\\y=0\end{cases}}\)
\(\left(xy-x\right)+\left(2y-2\right)=3\)
\(x.\left(y-1\right)+2.\left(y-1\right)=3\)
\(\left(y-1\right).\left(x+2\right)=3\)
\(\left(y-1\right).\left(x+2\right)=3.1=1.3=-3.-1=-1.-3\)
x+2 | 3 | 1 | -1 | -3 |
x | 1 | -1 | -3 | -5 |
y-1 | 1 | 3 | -3 | -1 |
y | 2 | 4 | -2 | 0 |
vậy các cặp (x;y) phải tìm lag (1;2) ; (-1;4) ; (-3;-2) ; (-5;0)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(3+3^2+.....+3^{99}\)
\(=\left(3+3^2+3^3\right)+\left(3^4+3^5+3^6\right)+...+\left(3^{97}+3^{98}+3^{99}\right)\)
\(=39+3^3\left(3+3^2+3^3\right)+........+3^{96}\left(3+3^2+3^3\right)\)
\(=39+3^3\cdot39+...+3^{96}\cdot39\)
\(=39\left(1+3^3+....+3^{96}\right)\)
Vì \(39⋮13\Rightarrow39\in B\left(13\right)\)
\(-5,2+3,5.\left(-2\right)-6,9:3+\left(-0,04\right)\\ =-5,2-7-2,3-0,04\\ =-5,2-3-0,04\\ =-8,24\)
TK:
=−5,2−7−2,3−0,04
=−5,2−3−0,04
=−8,24