\(\frac{2x-1}{-27}=\frac{3}{1-2x}\)

\(\Rightarrow\left(2x-1\right).\left(1-2x\right)=3.\left(-27\right)\)

\(-4x^2=-81\) ( chỗ này bn tự phân tích ra nha!)

\(x^2=\frac{-81}{-4}=\frac{81}{4}=\left(\frac{9}{2}\right)^2=\left(-\frac{9}{2}\right)^2\)

=>  x = 9/2 hoặc x = -9/2

lớp 5 thì có 

X=-6 hoặc x = 4/6

a, \(\frac{1}{\left(2x-3\right)^2}=9\Leftrightarrow\left(\frac{1}{2x-3}\right)^2=3^2\Leftrightarrow\frac{1}{2x-3}=3\Leftrightarrow1=6x-9\Leftrightarrow x=\frac{5}{3}\)

b, \(\frac{1}{\left(x-1\right)^3}=-\frac{1}{27}\Leftrightarrow\left(\frac{1}{x-1}\right)^3=\left(\frac{-1}{3}\right)^3\Leftrightarrow\frac{1}{x-1}=\frac{1}{-3}\Leftrightarrow x-1=-3\Leftrightarrow x=-2\)

c, \(\left(x-1\right)^2=\left(2x-5\right)^2\Leftrightarrow\orbr{\begin{cases}x-1=2x-5\\x-1=-2x+5\end{cases}\Leftrightarrow\orbr{\begin{cases}x=4\\x=2\end{cases}}}\)

\(MTC:\left(x-3\right)^2\left(x^2+3x+9\right)\)

\(\frac{x}{x^3-27}=\frac{x}{\left(x-3\right)\left(x^2+3x+9\right)}=\frac{x\left(x-3\right)}{\left(x-3\right)^2\left(x^2+3x+9\right)}\)

\(\frac{2x}{x^2-6x+9}=\frac{2x}{\left(x-3\right)^2}=\frac{2x\left(x^2+3x+9\right)}{\left(x-3\right)^2\left(x^2+3x+9\right)}\)

\(\frac{1}{x^2+3x+9}=\frac{\left(x-3\right)^2}{\left(x-3\right)^2\left(x^2+3x+9\right)}\)

\(MTC:2\left(x-1\right)\left(x+1\right)\)

\(\frac{x-1}{2x+2}=\frac{x-1}{2\left(x+1\right)}=\frac{\left(x-1\right)^2}{2\left(x-1\right)\left(x+1\right)}\)

\(\frac{x+1}{2x-2}=\frac{x+1}{2\left(x-1\right)}=\frac{\left(x+1\right)^2}{2\left(x-1\right)\left(x+1\right)}\)

\(\frac{1}{1-x^2}=-\frac{1}{\left(x-1\right)\left(x+1\right)}=-\frac{2}{2\left(x-1\right)\left(x+1\right)}\)

\(MTC:2\left(x+1\right)\left(x^2-x+1\right)\)

\(\frac{1}{x^3+1}=\frac{1}{\left(x+1\right)\left(x^2-x+1\right)}=\frac{2}{2\left(x+1\right)\left(x^2-x+1\right)}\)

\(\frac{3}{2x+2}=\frac{3}{2\left(x+1\right)}=\frac{3\left(x^2-x+1\right)}{2\left(x+1\right)\left(x^2-x+1\right)}\)

\(\frac{2}{x^2-x+1}=\frac{4\left(x+1\right)}{2\left(x+1\right)\left(x^2-x+1\right)}\)

(-1/3)^2x-1=-1/27

=>-1^2x-1/3^2x-1=1/27

Mà -1^2x-1=(-1)^2x/(-1)^1

                  =1/-1=-1

=>3^2x-1=27

=>3^2x/3^1=27

=>3^2x/3=27

=>3^2x=27*3

=>3^2x=81

=>3^2x=3^4

=>2x=4

=>x=2

t viết sai dấu vài chỗ ae thông cảm

ban co the sua lai duoc k 

\(\frac{2x-1}{3}=\frac{-27}{1-2x}\)

\(\Rightarrow\left(2x-1\right)\left(1-2x\right)=\left(-27\right).3\)

\(\Rightarrow2x-4x^2-1-2x=-81\)

\(\Rightarrow4x^2-1=-81\)

\(\Rightarrow4x^2=-81+1\)

\(\Rightarrow4x^2=-80\)

Vì \(x^2\ge0\)mà \(4x^2=-80\)

\(\Rightarrow x\in\theta\)

tíc mình nha