a) \(\left(\frac{-3}{4}\right)^{2n-1}=\frac{81}{256}\Leftrightarrow\left(\frac{-3}{4}\right)^{2n-1}=\left(\frac{-3}{4}\right)^4\)

<=>2n-1=4

<=>2n=5

<=>n=5/2

b)\(27<81^3:3^x<243\)

\(\Leftrightarrow3^3<3^{12}:3^x<3^5\)

=>3¹²:3^x=3⁴

=>3^x=3¹²:3⁴

=>3^x=3⁸

=>x=8

a,<=>\(x=\left(\frac{3}{5}\right)^2\)

<=>\(x=\frac{9}{25}\)

b,<=>\(x=-\frac{1}{3}\)

\(a,\left(\frac{3}{5}\right)^5.x=\left(\frac{3}{5}\right)^7\)

\(\Leftrightarrow x=\left(\frac{3}{5}\right)^7:\left(\frac{3}{5}\right)^5\)

\(\Leftrightarrow x=\left(\frac{3}{5}\right)^2=\frac{9}{25}\)

\(b,\left(-\frac{1}{3}\right)^3.x=\frac{1}{81}\)

\(\Leftrightarrow x=-\left[\left(\frac{1}{3}\right)^4:\left(\frac{1}{3}\right)^3\right]\)

\(\Leftrightarrow x=-\frac{1}{3}\)

\(10.3^x=81\)

\(3^x=80:10\)

\(3^x=8\)

\(\Rightarrow3^x=\varnothing\)

\(20-\left(x-1\right)^3=\frac{1}{16}\)

\(\left(x-1\right)^3=20-\frac{1}{16}\)

\(\left(x-1\right)^3=\frac{320}{16}-\frac{1}{16}\)

\(\left(x-1\right)^3=\frac{319}{16}\)

\(\Rightarrow\left(x-1\right)^3=\varnothing\Leftrightarrow x=\varnothing\)

a)

\(\Rightarrow3^x\left(3^2+3+1\right)=117\)

\(\Rightarrow3^x.13=117\)

\(\Rightarrow3^x=9\)

\(\Rightarrow3^x=3^2\)

=>x=2

b)

\(3^{2x+1}=3^{-4}\)

=> 2x+1= - 4

=>\(x=-\frac{5}{2}\)

c)

\(\left(x+2\right)^4=16\)

\(\Rightarrow\left[\begin{array}{nghiempt}\left(x+2\right)^4=2^4\\\left(x+2\right)^4=\left(-2\right)^4\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x+2=2\\x+2=-2\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\-4\end{array}\right.\)

thanks bn nhiu

a> => 2x ( 2x-1)³= -54

=>(2x-1)³=-27

=>2x-1=-9

=> 2x=-8

=>x=-4

 vậy x=-4

b>=>(1/3)^x=(1/3)⁴

=>x =4

  vậy x=4

  study well

Mình thấy nó cứ kiểu gì ý.Bạn có chắc là nó đúng ko vậy?

\(\left(x+1\right)^2=81\)

\(\Rightarrow\left(x+1\right)^2=9^2\)

\(\Rightarrow x+1=9\)

\(\Rightarrow x=9-1=8\)

Vậy x = 8

b, \(\left(x+5\right)^3=-64\)

\(\Rightarrow\left(x+5\right)^3=\left(-4\right)^3\)

\(\Rightarrow x+5=-4\)

\(\Rightarrow x=\left(-4\right)-5\)

\(\Rightarrow x=-9\)

Vậy x = -9

c, \(\left(2x-3\right)^2=9\)

\(\Rightarrow\left(2x-3\right)^2=3^2\)

\(\Rightarrow2x-3=3\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=3\)

Vậy x = 3

d, \(\left(4x+1\right)^3=27\)

\(\Rightarrow\left(4x+1\right)^3=3^3\)

\(\Rightarrow4x+1=3\)

\(\Rightarrow4x=2\)

\(\Rightarrow x=\frac{1}{2}\)

Vậy x = \(\frac{1}{2}\)

1/vì (1,78^2x-2-1,78^x):1,78^x=0

nên 1,78^x2-2-1,78^x=0     

=>1,78^2x-2=1,78^x

^=>2x-2=x

^2x=x+2

^=>x=2

2/vì cơ số bằng nhau nên ta có

x-2=1;-1;0

ta có:    x-2=1 =>  x=3

            x-2=-1 => x=1

             x-2=0 => x=2

3/ta có

(x+2)³=3³  =>x+2=3    =>x=1

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Đúng ko bạn