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a: \(=\dfrac{2^{10}\cdot3^8-2^{10}\cdot3^9}{2^{10}\cdot3^8+2^{10}\cdot3^8\cdot5}=\dfrac{2^{10}\cdot3^8\left(1-3\right)}{2^{10}\cdot3^8\left(1+5\right)}=\dfrac{-2}{6}=\dfrac{-1}{3}\)
b: \(=\dfrac{5^{16}\cdot3^{21}}{5^{15}\cdot3^{22}}=\dfrac{5}{3}\)
\(\dfrac{6^6+2^7.3^6+2^6.3^7}{4.2^3.3^2.2^2}\)
\(=\dfrac{\left(2^2.3\right)^6+2^7.3^6+2^6.3^7}{2^2.2^3.3^2.2^2}\)\(=\dfrac{2^{12}.3^6+2^7.3^6+2^6.3^7}{2^7.3^2}\)
\(=\dfrac{2^6.3^6.\left(2^6+2+3\right)}{2^7.3^2}\)\(=\dfrac{3^4.69}{2}=\dfrac{5589}{2}\)
\(\dfrac{4^5\cdot9^4\cdot5^7}{10^7\cdot27^3}=\dfrac{2^{10}\cdot3^8\cdot5^7}{5^7\cdot2^7\cdot3^9}=2^3\cdot\dfrac{1}{3}=\dfrac{8}{3}\)
a) \(5^{n+3}-5^{n+1}=5^{12}.120\Leftrightarrow5^{n+1}.\left(5^2-1\right)=5^{12}.5.24\)
\(\Leftrightarrow24.5^{n+1}=5^{13}.24\Leftrightarrow5^{n+1}=5^{13}\Leftrightarrow n+1=13\Leftrightarrow n=12\)
b) \(2^{n+1}+4.2^n=3.2^7\)
\(\Leftrightarrow2^n\left(2+4\right)=3.2^7\Leftrightarrow6.2^n=3.2^7\Leftrightarrow2^n=2^6\Leftrightarrow n=6\)
c) \(3^{n+2}-3^{n+1}=486\)
\(\Leftrightarrow3^{n+1}.\left(3-1\right)=486\Leftrightarrow2.3^{n+1}=486\Leftrightarrow3^{n+1}=243\)
\(\Leftrightarrow3^n=243:3=81=3^3\Leftrightarrow n=3\)
d) \(3^{2n+3}-3^{2n+2}=2.3^{10}\)
\(\Leftrightarrow3^{2n+2}.\left(3-1\right)=2.3^{10}\)
\(\Leftrightarrow3^{2n+2}.2=2.3^{10}\Leftrightarrow3^{2n+2}=3^{10}\Leftrightarrow2n+2=10\Leftrightarrow2n=8\Leftrightarrow n=4\)
a, \(3^{-2}.3^4.3^x=3^7\)
\(\Rightarrow3^{-2+4+x}=3^7\)
\(\Rightarrow3^{2+x}=3^7\)
Vì \(3\ne\pm1;3\ne0\) nên \(2+x=7\Rightarrow x=5\)
b, \(2^{-1}.2^x+4.2^x=9.2^5\)
\(\Rightarrow2^x\left(2^{-1}+4\right)=288\)
\(\Rightarrow2^x.4,5=288\Rightarrow2^x=64=2^6\)
Vì \(2\ne\pm1;2\ne0\) nên \(x=6\)
Chúc bạn học tốt!!!
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đề bài là tính hả bn?