a)81^-2x*27^x=95
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\(81^{-2x}.27^x=95\)
1)tìm x biết:
a)(x-2)^2=1
b)(2x-1)^3=-8
c)(x+1/2)^2=1/16
d)(x-2)^3=-27
e(2x-3)^2=25
g)3^x-1=1/243
h)2^x+2^x+3=144
k)81^-2x*27^x=95
a) (X - 2)\(^2\) = 1 <=> X - 2 = \(\sqrt{1}\) <=> X = 1 + 2 <=> X = 3
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1)tìm x biết:
a)(x-2)^2=1
b)(2x-1)^3=-8
c)(x+1/2)^2=1/16
d)(x-2)^3=-27
e(2x-3)^2=25
g)3^x-1=1/243
h)2^x+2^x+3=144
k)81^-2x*27^x=95
a. (x - 2)2 = 1
<=> (x - 2)2 = 12 = (-1)2
<=> \(\begin{cases}x-2=1\\x-2=-1\end{cases}\Leftrightarrow\begin{cases}x=3\\x=1\end{cases}\)
Vậy x \(\in\){1; 3}.
b. (2x - 1)3 = -8
<=> (2x - 1)3 = (-2)3
<=> 2x - 1 = -2
<=> 2x = -2 + 1
<=> 2x = -1
<=> x = -1/2
Vậy x = -1/2.
c. (x + 1/2)2 = 1/16
<=> (x + 1/2)2 = (1/4)2 = (-1/4)2
<=> \(\begin{cases}x+\frac{1}{2}=\frac{1}{4}\\x+\frac{1}{2}=-\frac{1}{4}\end{cases}\Leftrightarrow\begin{cases}x=-\frac{1}{4}\\x=-\frac{3}{4}\end{cases}\)
Vậy x \(\in\){-1/4; -3/4}.
d. (x - 2)3 = -27
<=> (x - 2)3 = (-3)3
<=> x - 2 = -3
<=> x = -3 + 2
<=> x = -1
Vậy x = -1.
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a.\(\left(x-2\right)^2\)=1
<=> x-2=1 hoặc x-2=-1
<=> x= 3 hoặc x=1
b.\(\left(2x-1\right)^3\)=-8
\(\left(2x-1\right)^3\)=\(\left(-2\right)^3\)
2x-1=-2
2x=-1
x=-1/2
c.\(\left(x+\frac{1}{2}\right)^2\)=\(\frac{1}{16}\)
\(\left(x+\frac{1}{2}\right)^2\)=\(\left(\frac{1}{4}\right)^2\)hoặc \(\left(x+\frac{1}{2}\right)^2\)=\(\left(-\frac{1}{4}\right)^2\)
x+\(\frac{1}{2}\)=\(\frac{1}{4}\) hoặc x+\(\frac{1}{2}\)=-\(\frac{1}{4}\)
x=-\(\frac{1}{4}\)hoặc x=-\(\frac{3}{4}\)
d.\(\left(x-2\right)^3\)=-27
\(\left(x-2\right)^3\)=\(\left(-3\right)^3\)
x-2=-3
x=-1
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g.\(3^{x-1}\)=\(\frac{1}{243}\)
\(3^{x-1}\)=\(\frac{1}{3^5}\)
\(3^{x-1}\)=\(3^{-5}\)
x-1=-5
x=-4
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Tính
A. ( -25 -35) : 12 - (-198)
B. 19 - (-67) - 67 : 81 -3200
C. (-3)12 : 813 - (-498) + 22
D. 49 (27 - 95) - 27 (49 - 95)
E. 12 . 4 - 24 (2-79) + 79 . 76
Tìm x biết a) 2x+2^(x+3) =144
b) 81^(-2x)*27^x =9^5
tìm x, biết:
a. 2 . 3x - 405 = 3^x - 1
b.(1/81)^x . 27^2x = (-9)^4
Tìm x;ý biết :
a) ( x+11+y) + (x -4-y) =0
b). 81^-2x * 27^x =9^5
Tìm x:a) dfrac{2}{3}+left(x-dfrac{1}{2}right)^3dfrac{19}{27}b) left(dfrac{3}{2}right)^{2x-1}:left(dfrac{27}{8}right)^3dfrac{81}{16}c) dfrac{1}{2}.2^x+4.2^x9.2^5d) text{12 - (2x +1)}^2-69
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Tìm x:
\(a\)) \(\dfrac{2}{3}+\left(x-\dfrac{1}{2}\right)^3=\dfrac{19}{27}\)
\(b\)) \(\left(\dfrac{3}{2}\right)^{2x-1}:\left(\dfrac{27}{8}\right)^3=\dfrac{81}{16}\)
\(c\)) \(\dfrac{1}{2}.2^x+4.2^x=9.2^5\)
\(d\)) \(\text{12 - (2x +1)}^2=-69\)
\(a,\Rightarrow\left(x-\dfrac{1}{2}\right)^3=\dfrac{1}{27}=\left(\dfrac{1}{3}\right)^3\\ \Rightarrow x-\dfrac{1}{2}=\dfrac{1}{3}\Rightarrow x=\dfrac{5}{6}\\ b,\Rightarrow\left(\dfrac{3}{2}\right)^{2x-1}:\left(\dfrac{3}{2}\right)^9=\left(\dfrac{3}{2}\right)^4\\ \Rightarrow2x-1-9=4\\ \Rightarrow2x=14\Rightarrow x=7\\ c,\Rightarrow2^{x-1}+2^{x+2}=9\cdot2^5\\ \Rightarrow2^{x-1}\left(1+2^3\right)=9\cdot2^5\\ \Rightarrow2^{x-1}\cdot9=9\cdot2^5\\ \Rightarrow2^{x-1}=2^5\Rightarrow x-1=5\Rightarrow x=6\\ d,\Rightarrow\left(2x+1\right)^2=12+69=81\\ \Rightarrow\left[{}\begin{matrix}2x+1=9\\2x+1=-9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-5\end{matrix}\right.\)
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\(a,\dfrac{2}{3}+\left(x-\dfrac{1}{2}\right)^3=\dfrac{19}{27}\)
\(\left(x-\dfrac{1}{2}\right)^3=\dfrac{19}{27}-\dfrac{2}{3}\)
\(\left(x-\dfrac{1}{2}\right)^3=\dfrac{1}{27}\)
\(\Rightarrow\left(x-\dfrac{1}{2}\right)^3=\left(\dfrac{1}{3}\right)^3\)
\(\Rightarrow x-\dfrac{1}{2}=\dfrac{1}{3}\)
\(x=\dfrac{1}{2}+\dfrac{1}{3}\)
\(x=\dfrac{1}{5}\)
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Tìm x:
a)(1/3)^x=1/729
b)(1/3-1/2)^x-1 =1/36
c)81^2x . 27^x = -27
d)(x-2)^2 =1