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Bài 3:
\(\Leftrightarrow3^{2x+6}=3\)
=>2x+6=1
=>2x=-5
hay x=-5/2
a/ 72+x + 2.7x-1 =345
73 . 7x-1 + 2.7x-1 = 345
7x-1 (73+2) = 345
7x-1 . 345 = 345
7x-1 = 345 : 345 = 1
7x-1 = 70
x - 1 = 0
x = 0+1 = 1
b/ 81-2x . 27x = 95
(34)-2x . (33)x = (32)5
34.(-2x) . 33.x = 32.5
3-8x . 33x = 310
3-8x+3x = 310
3-5x = 310
-5x = 10
x = 10 : (-5) = -2
1.a) \(\left(\frac{3}{5}\right)^{15}:\left(\frac{9}{25}\right)^5=\frac{3^{15}}{5^{15}}.\frac{5^{10}}{3^{10}}=\frac{3^5}{5^5}=\left(\frac{3}{5}\right)^5\)
b)\(\left(\frac{2}{3}\right)^{10}:\left(\frac{4}{9}\right)^4=\frac{2^{10}}{3^{10}}.\frac{3^8}{2^8}=\frac{2^2}{3^2}=\left(\frac{2}{3}\right)^2\)
2.
a)\(2^x=4\Rightarrow2^x=2^2\Rightarrow x=2\)
b)\(x^3=-27\Rightarrow x^3=-3^3\Rightarrow x=-3\)
c)\(x^2=16\Rightarrow x=\pm4\)
d)\(\left(x+1\right)^2=9\Rightarrow\hept{\begin{cases}x+1=3\Rightarrow x=2\\x+1=-3\Rightarrow x=-4\end{cases}}\)
1) Tìm số nguyên x, biết :
a) 3x = 94/ 273
3x = 1/3
3x = 3-1
=> x = -1
b) 3x = 98 / 273 . 812
3x = 37.38
3x = 315
=> x = 15
c) 2x - 3 / 410 = 83
2x - 3 = 83.410
2x - 3 = 226
=> x - 3 = 26
=> x = 29
d) 22x - 3 / 410 = 83 . 165
22x - 3 / 410 = 269
22x - 3 = 269 . 410
22x - 3 = 289
=> 2x - 3 = 89
2x = 91
x = 91/2
e) 35 / 3x = 310
3x = 35 : 310
3x = 3-5
=> x = -5
a) \(2^{x+1}\cdot3^y=12^x\Leftrightarrow2^{x+1}\cdot3^y=2^{2x}\cdot3^x\)
\(\Rightarrow\left\{{}\begin{matrix}x+1=2x\\y=x\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)
b) \(10^x:5^y=20^y\Leftrightarrow20^y\cdot5^y=10^x\Leftrightarrow\left(20\cdot5\right)^y=10^x\Leftrightarrow100^y=10^x\Leftrightarrow10^{2y}=10^x\Leftrightarrow2y=x\)
c) \(\left\{{}\begin{matrix}2^x=4^{y-1}\\27^y=3^{x+8}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2^x=2^{2y-2}\\3^{3y}=3^{x+8}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2y-2\\3y=x+8\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=2y-2\\3y=2y-2+8\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=10\\y=6\end{matrix}\right.\)
a) 27x : 3x = 9
(27 : 3)x = 9
9x = 91
x = 1
b) 25 : 5x =5
5x = 25 : 5
5x = 51
x = 1
c) 2 : (x + 2)2 = \(\dfrac{1}{18}\)
(x + 2)2 = 2 : \(\dfrac{1}{18}\)
(x + 2)2 = 36
\(\Rightarrow\left[{}\begin{matrix}x+2=6\\x+2=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-8\end{matrix}\right.\)
d) (5x - 1)2 = \(\dfrac{36}{49}\)
(5x - 1)2 = \(\left(\dfrac{6}{7}\right)^2\)
Bạn làm tiếp nha, mình có việc bận :v
1, 27x.9x=927:81
(33)x.(32)X=(32)27:34
33X.32X=354:34
33X+2X=350
35X=350
Suy ra :5x=50
x=10
\(a,3^x=\frac{9^4}{27^3}\)
\(\Leftrightarrow3^x=3^8:3^9\)
\(\Leftrightarrow3^x=3^{-1}\)
\(\Leftrightarrow x=-1\)
\(b,\frac{5^5}{5^x}=5^{18}\)
\(\Leftrightarrow5^x=5^5:5^{18}\)
\(\Leftrightarrow5^x=5^{-13}\)
\(\Leftrightarrow x=-13\)
A;3x=94/(9*3) 3=94=93*33=93*9=94
3X=94=38
X=8
B;55/5x=518=55-x
=>5-x=18
x=5-18
x=-13