Tìm x bt : 3^x+1+3^x+2-2.3^x=270(đề bài ko sai tí nào nha)
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3x+3x-1+3x-2=1053
=> 3x-2.32+3x-2.3+3x-2=1053
3x-2.9+3x-2.3+3x-2=1053
=>3x-2.(9+3+1)=1053
3x-2.13=1053
3x-2=1053:13=81
3x-2=34
=>x-2=4
x=4+2
x=6
a, 7\(x\) - \(x\) = 521 : 519 + 3.22.7
6\(x\) = 53 + 3.4.7
6\(x\) = 125 + 12.7
6\(x\) = 125 + 84
6\(x\) = 209
\(x\) = 209 : 6
\(x\) = \(\dfrac{209}{6}\)
b; 11\(x\) - 7\(x\) + 34 : 33 = 54 + 2\(x\)
4\(x\) + 3 = 625 + 2\(x\)
4\(x\) - 2\(x\) = 625 - 3
2\(x\) = 622
\(x\) = 622 : 2
\(x\) = 311
c; 75 - 5.(\(x-3\))3 = 700
5.(\(x\) - 3)3 = 700 - 75
5.(\(x\) - 3)3 = - 625
(\(x\) - 30)3 = - 625 : 5
(\(x\) - 30)3 = - 125
(\(x-3\))3 = (-5)3
\(x\) - 3 = - 5
\(x\) = - 5 + 3
\(x\) = -2
d, 3.(2\(x\) - 1)2 = 75
(2\(x\) - 1)2 = 75 : 3
(2\(x\) - 1)2 = 25
\(\left[{}\begin{matrix}2x-1=-5\\2x-1=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-5+1\\2x=5+1\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-4\\2x=6\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)
72x-3moi dung
=>72x-3-5.72=72.2
=> 72x-3=72.2+72.5
=> 72x-3=72(2+5)
=>72x-3=72.7=73
=> 2x-3=3
=> 2x= 3+3
=>2x=6
=>x=6:2
=>x=3
Vay x =3
Bai lam
\(3^{x+1}=9^x\Leftrightarrow3^{x+1}=3^{2x}\)
\(\Leftrightarrow x-1=2x\Leftrightarrow-x-1=0\Leftrightarrow x=-1\)
\(3^{x+1}+3^{x+2}-2.3^x=270\\ \Leftrightarrow3^x.3+3^x.3^2-2.3^x=270\\ \Leftrightarrow3^x.\left(3+3^2-2\right)=270\\ \Leftrightarrow3^x.10=270\\ \Leftrightarrow3^x=270:10\\ \Leftrightarrow3^x=27\\ \Leftrightarrow3^x=3^3\\ \Leftrightarrow x=3\)