giúp với
(1/3)x=1/81
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\(\left(\frac{-1}{3}\right)^8:x=\frac{1}{81}\)
\(\frac{\left(-1\right)^8}{3^8}:x=\frac{1}{9^2}\)
\(\frac{1}{\left(3^2\right)^4}:x=\frac{1}{9^2}\)
\(\frac{1}{9^4}:x=\frac{1}{9^2}\)
\(x=\frac{1}{9^4}:\frac{1}{9^2}\)
\(x=\frac{1}{9^4}.9^2\)
\(x=\frac{1}{9^2}\)
\(x=\frac{1}{81}\)
Vậy \(x=\frac{1}{81}\)
\(\left(\frac{-1}{3}\right)^8\div x=\frac{1}{81}\)
\(\frac{1}{6561}\div x=\frac{1}{81}\)
\(x=\frac{1}{6561}\div\frac{1}{81}\)
\(x=\frac{1}{81}\)
a: \(2^6\cdot3^3=\left(2^2\cdot3\right)^3=12^3\)
b: \(6^4\cdot8^3=2^4\cdot3^4\cdot2^9=2^{13}\cdot3^4\)
c: \(16\cdot81=36^2\)
d: \(25^4\cdot2^8=100^4\)
(x+1/2)mũ 3 : 3 = -1/81
(x+1/2)mũ 3 = -1/81 . 3
(x+1/2)mũ 3 = -1/27
(x+1/2)mũ 3 = (-1/3)mũ3
x+1/2 = -1/3
x = -1/3 - 1/2
x = -5/6
\(3S=241+81+27+9+...+\dfrac{1}{9}+\dfrac{1}{27}\)
\(2S=3S-S=241-\dfrac{1}{81}=\dfrac{241x81-1}{81}\)
\(\Rightarrow S=\dfrac{241x81-1}{2x81}\)
a) \(\dfrac{49}{81}=\dfrac{7^x}{9^x}\)(sửa đề)
\(\Leftrightarrow\left(\dfrac{7}{9}\right)^2=\left(\dfrac{7}{9}\right)^x\)\(\Rightarrow x=2\)
b) \(\dfrac{-64}{343}=\left(-\dfrac{4^x}{7^x}\right)\)(sửa đề)
\(\Leftrightarrow\left(-\dfrac{4}{7}\right)^3=\left(-\dfrac{4}{7}\right)^x\) \(\Rightarrow x=3\)
c) \(\dfrac{9}{144}=\dfrac{3^x}{12^x}\)(sửa đề)
\(\Leftrightarrow\left(\dfrac{3}{12}\right)^2=\left(\dfrac{3}{12}\right)^x\Rightarrow x=2\)
d) \(-\dfrac{1}{32}=\left(-\dfrac{1^x}{2^x}\right)\)(sửa đề)
\(\Leftrightarrow\left(-\dfrac{1}{2}\right)^5=\left(-\dfrac{1}{2}\right)^x\Rightarrow x=5\)
Mong bạn xem lại đề bài.
a. ( 2x + 1 )2 = 49
<=> ( 2x + 1 )2 = 72
<=> 2x + 1 = 7
<=> x = 3
b. ( 2x - 1 )4 = 81
<=> ( 2x - 1 )4 = 34
<=> 2x - 1 = 3
<=> x = 2
c. ( x + 1 )3 = 2x3
<=> x + 1 = 2x
<=> x = 1
d. ( 2x + 1 )3 = 3x3
<=> 2x + 1 = 3x
<=> x = 1
( 2x + 1 )2 = 49
<=> ( 2x + 1 )2 = ( ±7 )2
<=> \(\orbr{\begin{cases}2x+1=7\\2x+1=-7\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=-4\end{cases}}\)
( 2x - 1 )4 = 81
<=> ( 2x - 1 )4 = ( ±3 )4
<=> \(\orbr{\begin{cases}2x-1=3\\2x-1=-3\end{cases}}\Rightarrow\orbr{\begin{cases}x=2\\x=-1\end{cases}}\)
( x + 1 )3 = ( 2x )3
<=> x + 1 = 2x
<=> x - 2x = -1
<=> -x = -1
<=> x = 1
( 2x + 1 )3 = ( 3x )3
<=> 2x + 1 = 3x
<=> 2x - 3x = -1
<=> -x = -1
<=> x = 1
\(\left(\dfrac{1}{3}\right)^x=\dfrac{1}{81}\)
\(\left(\dfrac{1}{3}\right)^x=\left(\dfrac{1}{3}\right)^4\)
=> x = 4
(1/3) mũ x= (1/3) mũ 4
x=4