Tìm x thuộc N
\(8< 2^x\le2^9.2^{-5}\)
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Tìm x ∈ N biết :
a) \(8< 2^x\le2^9.2^{-5}\)
b)\(27< 81^3:3^x< 243\)
c)\(\left(\dfrac{2}{5}\right)^x>\left(\dfrac{5}{2}\right)^{-3}.\left(\dfrac{-3}{5}\right)^2\)
\(a,\Rightarrow2^3< 2^x\le2^4\Rightarrow x=4\\ b,\Rightarrow3^3< 3^{12}:3^x< 3^5\\ \Rightarrow3^3< 3^{12-x}< 3^5\\ \Rightarrow12-x=4\Rightarrow x=8\)
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Tìm x thuộc N:\(8< 2^x< 2^9.2^{-5}\)
8<2x<29.2-5
23 < 2x< 24
=> x thuộc rỗng ( viết bằng kí hiệu )
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Tìm x \(\in\) N biết :
a)\(8< 2^x\le2^9.2^{-5}\)
b) \(27< 81^3:3^x< 243\)
c)\(\left(\frac{2}{5}\right)^x>\left(\frac{5}{2}\right)^{-3}.\left(\frac{-2}{5}\right)^2\)
a,\(8< 2^x\le2^9.2^{-5}\)
\(2^3< 2^x\le2^4\)
\(\Rightarrow x=4\)
b, \(27< 81^3.3^x< 243\)
\(3^3< 3^{12-x}< 3^5\)
\(\Rightarrow3< 12-x< 5\)
12-x=4
x=8
c,\(\left(\frac{2}{5}\right)^x>\left(\frac{2}{5}\right)^3.\left(\frac{2}{5}\right)^2\)
\(\left(\frac{2}{5}\right)^x>\left(\frac{2}{5}\right)^5\)
\(\Rightarrow x>5\)
x=6;7;8........
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Tìm x
a) 8<\(2^x\le2^9.2^{-5}\) b) 27<\(81^3:3^x< 243\)
a, 8 < 2x \(\le\) 29 . 2-5
=> 23 < 2x \(\le\) 2 (9-5)
=> 23 < 2x \(\le\) 24
=> x = 4
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Tìm x
a) 8<\(2^x\le2^9.2^{-5}\) b) 27<\(81^3:3^x< 243\)
Giải :
a,Ta có :
\(8=2^3\\ 2^9.2^{-5}=2^4\)
\(\Rightarrow2^3< 2^x< 2^4\)
\(\Rightarrow3< x< 4\left(x\in R\right)\)
b, Ta có :
\(27=3^3\\ 81^3:3^x=3^{12}:3^x=3^{12-x}\\ 243=3^5\)
\(\Rightarrow3^3< 3^{12-x}< 3^5\)
\(\Rightarrow3< 12-x< 5\)
\(\Rightarrow7< x< 9\left(x\in R\right)\)
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Tìm x
a) 8<\(2^x\le2^9.2^{-5}\) b) 27<\(81^3:3^x< 243\)
\(8< 2^x\le2^9.2^{-5}\)
\(\Leftrightarrow2^3< 2^x\le2^9.\dfrac{1}{2^5}\)
\(\Leftrightarrow2^3< 2^x\le2^4\)
\(\Leftrightarrow x=4\)
Vậy \(x=4\)
\(27< 81^3:3^x< 243\)
\(\Leftrightarrow3^3< \left(3^4\right)^3:3^x< 3^5\)
\(\Leftrightarrow3^3< 3^{12}:3^x< 3^5\)
\(\Leftrightarrow3^3< 3^{12-x}< 3^5\)
\(\Leftrightarrow3^{12-x}=3^4\)
\(\Leftrightarrow12-x=4\)
\(\Leftrightarrow x=4\)
Vậy \(x=4\)
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Tìm x
a) 8<\(2^x\le2^9.2^{-5}\) b) 27<\(81^3:3^x< 243\)
\(a)8< 2^x\le2^9.2^{-5}\)
\(\Leftrightarrow2^3< 2^x\le2^9.\dfrac{1}{2^5}\)
\(\Leftrightarrow2^3< 2^x\le2^4\)
\(\Leftrightarrow x=4\)
\(b)27< 81^3:3^x< 243\)
\(\Leftrightarrow3^3< \left(3^4\right)^3:3^x< 3^5\)
\(\Leftrightarrow3^3< 3^{12}:3^x< 3^5\)
\(\Leftrightarrow3^3< 3^{12-x}< 3^5\)
\(\Leftrightarrow12-x=4\)
\(\Leftrightarrow x=8\)
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tìm x thuộc N
a. \(8< 2^x< =2^9.2^{-5}\)
b .27<\(81^3\):\(3^x< 243\)
c . \(\left(\frac{2}{5}\right)^x>\left(\frac{5}{2}\right)^{-3}.\left(\frac{2}{5}\right)^2\)
a) \(8< 2^x\le2^9.2^{-5}\)
\(\Leftrightarrow2^3< x\le2^{9-5}\)
\(\Leftrightarrow2^3< 2^x\le2^4\)
\(\Leftrightarrow3< x\le4\Leftrightarrow x=4\)
b) \(27< 81^3:3^x< 243\)
\(\Leftrightarrow3^2< \left(3^4\right)^3:3^x< 3^5\)
\(\Leftrightarrow3^2< 3^{12}:3^x< 3^5\)
\(\Leftrightarrow3^2< 3^{12-x}< 3^5\)
\(\Leftrightarrow2< 12-x< 5\)
\(\Leftrightarrow\hept{\begin{cases}x=8\\x=9\end{cases}}\)
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Tìm x thuộc Z
a)\(32^{-n}.16^n=2048\)
b)\(2^{-1}.2^n+4.2^n=9.2^5\)
a)\(32^{-n}\cdot16^n=2048\)
\(\left(2^5\right)^{-n}\cdot\left(2^4\right)^n\)=2048
\(2^{-5n}\cdot2^{4n}\)=\(2^{11}\)
\(2^{-5n+4n}=2^{11}\)
\(2^{-x}=2^{11}\)
\(\Rightarrow x=-11\)
b)\(2^{-1}\cdot2^n+4\cdot2^n=9\cdot2^5\)
\(\frac{1}{2}\cdot2^n+4\cdot2^n=288\)
\(2^n\left(\frac{1}{2}+4\right)=288\)
\(2^n\cdot\frac{9}{2}=288\)
\(2^n=288:\frac{9}{2}\)
\(2^n=64\)
\(2^n=2^6\)
\(\Rightarrow n=6\)
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a) 32-n . 16n = 2048
\(\frac{1}{32n}\) . 16n = 2048
\(\frac{1}{2^n.16^n}\) . 16n = 2048
\(\frac{1}{2^n}\) = 2048
2-n = 2048
2-n = 211
\(\Rightarrow\) -n = 11
\(\Rightarrow\) n = -11
Vậy n = -11
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