2375 x y + =276
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\(5^x-5^{x-1}-5^{x-2}=2375\\ \Leftrightarrow5^x-\dfrac{5^x}{5}-\dfrac{5^x}{25}=2375\\ \Leftrightarrow5^x\left(1-\dfrac{1}{5}-\dfrac{1}{25}\right)=2375\\ \Leftrightarrow5^x.\dfrac{19}{25}=2375\\ \Leftrightarrow5^x=3125\\ \Leftrightarrow5^x=5^5\\ \Leftrightarrow x=5\)
\(5^x-5^{x-1}-5^{x-2}=2375\)
\(\Rightarrow5^{x-2}\left(5^2-5^1-1\right)=2375\)
\(\Rightarrow5^{x-2}.19=2375\)
\(\Rightarrow5^{x-2}=125=5^3\Rightarrow x-2=3\Rightarrow x=5\)
Ta có: \(9\cdot5^{x-2}+7\cdot5^{x-1}-5^x=2375\)
\(\Leftrightarrow5^x\cdot\dfrac{9}{25}+5^x\cdot\dfrac{7}{5}-5^x\cdot1=2375\)
\(\Leftrightarrow5^x\cdot\dfrac{19}{25}=2375\)
\(\Leftrightarrow5^x=2375:\dfrac{19}{25}=2375\cdot\dfrac{25}{19}=3125\)
\(\Leftrightarrow5^x=5^5\)
hay x=5
Vậy: x=5
`2375 xx (72 : 8) + 49`
`= 2375 xx 9 + 49`
`= 21424`
_____________________
`2375 xx (72 : 9) + 49`
`= 2375 xx 8 + 49`
`= 19049`
Thay n=8, ta có:
2375 x ( 72 : 8 ) + 49
= 21424
Thay n=9, ta có:
2375 x ( 72 : 9 ) + 49
=19049
=100000-(47.(75+24+1) b) =276.(50+36+4)
=100000-4700 =276.90
=95300 =24840
\(100000-\left(47.75+47.24+47\right)\)
\(=100000-\left(47.75+47.24+47.1\right)\)
\(=100000-\left[47.\left(75+24+1\right)\right]\)
\(=100000-47.100\)
\(=100000-47000\)
\(=53000\)
\(276.50+276.36+1104\)
\(=276.50+276.36+276.4\)
\(=276.\left(50+36+4\right)\)
\(=276.90\)
\(=24840\)