3^2×1/243×81^2×1/3^3
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`@` `\text {Ans}`
`\downarrow`
\(3^2\cdot\dfrac{1}{243}\cdot81^2\cdot\dfrac{1}{3^3}\)
`=`\(\dfrac{3^2}{243}\cdot\dfrac{81^2}{3^3}\)
`=`\(\dfrac{3^2}{3^5}\cdot\dfrac{3^8}{3^3}=\dfrac{1}{3^3}\cdot3^5=\dfrac{3^5}{3^3}=3^2=9\)
\(3^2\cdot\dfrac{1}{243}\cdot81^2\cdot\dfrac{1}{3^2}\)
\(=3^2\cdot\dfrac{1}{3^5}\cdot\left(3^4\right)^2\cdot\dfrac{1}{3^2}\)
\(=3^2\cdot\dfrac{1}{3^5}\cdot3^8\cdot\dfrac{1}{3^2}\)
\(=\dfrac{3^2}{3^5}\cdot\dfrac{3^8}{3^2}\)
\(=\dfrac{3^2}{3^5}\cdot3^6\)
\(=\dfrac{3^2\cdot3^6}{3^5}\)
\(=3^2\cdot3\)
\(=3^3\)
\(=27\)
\(8;a,3^2.\frac{1}{243}.81^2.\frac{1}{3^3}\)
\(=\frac{3^2.\left(3^4\right)^2}{243.3^3}\)
\(=\frac{3^2.3^8}{3^5.3^3}\)
\(=\frac{3^{10}}{3^8}=3^2=9\)
\(b,\frac{4.2^5}{2^3.\frac{1}{16}}\)
\(=\frac{2^2.2^5}{2^3.\frac{1}{2^4}}\)
\(=\frac{2^7}{\frac{1}{2}}=2^7.2=2^8\)
a, \(3^2.\frac{1}{243}.81^2.\frac{1}{3}^3\)
\(=3^2.\frac{1}{243}.\left(3^4\right)^2.\frac{1}{27}\)
\(=3^2.\frac{1}{243}.3^8.\frac{1}{27}\)
\(=\frac{3^2.3^8}{243.27}\)
\(=\frac{3^2.3^8}{3^5.3^3}\)
\(=\frac{3^{10}}{3^8}=3^2=9\)
b, \(\left(4.2^5\right):\left(2^3.\frac{1}{16}\right)\)
\(=\left(2^2.2^5\right):\left(8.\frac{1}{16}\right)\)
\(=2^7:\frac{1}{2}\)
\(=2^8\)
\(1-\frac{2}{3}-\frac{2}{9}-\frac{2}{27}-\frac{2}{81}-\frac{2}{243}\)
\(=\frac{243}{243}-\frac{162}{243}-\frac{54}{243}-\frac{6}{243}-\frac{2}{243}=\frac{1}{243}\)
Nông Hà Thanh
\(3^2.\frac{1}{243}.81^2.\frac{1}{3^2}\)
\(=\frac{3^2}{3^5}.\frac{81^2}{3^2}\)
\(=\frac{1}{3^3}.27^2\)
\(=\frac{27^2}{3^3}\)
\(=\frac{3^6}{3^3}\)
\(=3^2\)
\(=9\)
a: \(2^{x^2-1}=256\)
=>\(2^{x^2-1}=2^8\)
=>\(x^2-1=8\)
=>\(x^2=9\)
=>\(x\in\left\{3;-3\right\}\)
b: \(3^{x^2+3x}=81\)
=>\(3^{x^2+3x}=3^4\)
=>\(x^2+3x=4\)
=>\(x^2+3x-4=0\)
=>(x+4)(x-1)=0
=>\(\left[{}\begin{matrix}x+4=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-4\\x=1\end{matrix}\right.\)
c: \(2^{x^2-5x}=64\)
=>\(2^{x^2-5x}=2^6\)
=>\(x^2-5x=6\)
=>\(x^2-5x-6=0\)
=>(x-6)(x+1)=0
=>\(\left[{}\begin{matrix}x-6=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-1\end{matrix}\right.\)
d: \(\left(\dfrac{1}{3}\right)^x=243\)
=>\(\left(\dfrac{1}{3}\right)^x=3^5=\left(\dfrac{1}{3}\right)^{-5}\)
=>x=-5
e: \(\left(\dfrac{1}{3}\right)^{x+5}=3^{2x+1}\)
=>\(3^{-x-5}=3^{2x+1}\)
=>-x-5=2x+1
=>-3x=6
=>x=-2