\(\frac{2x-1}{3}=\frac{-27}{1-2x}\)Tính x
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\(MTC:\left(x-3\right)^2\left(x^2+3x+9\right)\)
\(\frac{x}{x^3-27}=\frac{x}{\left(x-3\right)\left(x^2+3x+9\right)}=\frac{x\left(x-3\right)}{\left(x-3\right)^2\left(x^2+3x+9\right)}\)
\(\frac{2x}{x^2-6x+9}=\frac{2x}{\left(x-3\right)^2}=\frac{2x\left(x^2+3x+9\right)}{\left(x-3\right)^2\left(x^2+3x+9\right)}\)
\(\frac{1}{x^2+3x+9}=\frac{\left(x-3\right)^2}{\left(x-3\right)^2\left(x^2+3x+9\right)}\)
\(MTC:2\left(x-1\right)\left(x+1\right)\)
\(\frac{x-1}{2x+2}=\frac{x-1}{2\left(x+1\right)}=\frac{\left(x-1\right)^2}{2\left(x-1\right)\left(x+1\right)}\)
\(\frac{x+1}{2x-2}=\frac{x+1}{2\left(x-1\right)}=\frac{\left(x+1\right)^2}{2\left(x-1\right)\left(x+1\right)}\)
\(\frac{1}{1-x^2}=-\frac{1}{\left(x-1\right)\left(x+1\right)}=-\frac{2}{2\left(x-1\right)\left(x+1\right)}\)
\(MTC:2\left(x+1\right)\left(x^2-x+1\right)\)
\(\frac{1}{x^3+1}=\frac{1}{\left(x+1\right)\left(x^2-x+1\right)}=\frac{2}{2\left(x+1\right)\left(x^2-x+1\right)}\)
\(\frac{3}{2x+2}=\frac{3}{2\left(x+1\right)}=\frac{3\left(x^2-x+1\right)}{2\left(x+1\right)\left(x^2-x+1\right)}\)
\(\frac{2}{x^2-x+1}=\frac{4\left(x+1\right)}{2\left(x+1\right)\left(x^2-x+1\right)}\)
\(\frac{2x-1}{-27}=\frac{3}{1-2x}\)
\(\Rightarrow\left(2x-1\right).\left(1-2x\right)=3.\left(-27\right)\)
\(-4x^2=-81\) ( 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
\(1+\frac{2x}{x+4}+\frac{27}{2x^2+7x-4}=\frac{6}{2x-1}\left(x\ne-4;x\ne\frac{1}{2}\right)\)
\(\Leftrightarrow1+\frac{2x}{x+4}+\frac{27}{\left(x+4\right)\left(2x-1\right)}-\frac{6}{2x-1}=0\)
\(\Leftrightarrow\frac{2x^2+7x-4}{\left(x+4\right)\left(2x-1\right)}+\frac{2x\left(2x-1\right)}{\left(x+4\right)\left(2x-1\right)}+\frac{27}{\left(x+4\right)\left(2x-1\right)}-\frac{6\left(x+4\right)}{\left(x+4\right)\left(2x-1\right)}=0\)
\(\Leftrightarrow\frac{2x^2+7x-4}{\left(x+4\right)\left(2x-1\right)}+\frac{4x^2-2x}{\left(x+4\right)\left(2x-1\right)}+\frac{27}{\left(x+4\right)\left(2x-1\right)}-\frac{6x+24}{\left(x+4\right)\left(2x-1\right)}=0\)
\(\Leftrightarrow\frac{2x^2+7x-4+4x^2-2x+27-6x-24}{\left(x+4\right)\left(2x-1\right)}=0\)
\(\Leftrightarrow\frac{6x^2-x-1}{\left(x+4\right)\left(2x-1\right)}=0\)
\(\Leftrightarrow6x^2-x-1=0\)
\(\Leftrightarrow6x^2+2x-3x-1=0\)
<=> 2x(3x+1)-(3x+1)=0
<=> (3x+1)(2x-1)=0
\(\Leftrightarrow\orbr{\begin{cases}3x+1=0\\2x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{-1}{3}\left(tm\right)\\x=\frac{1}{2}\left(ktm\right)\end{cases}}}\)
Vậy pt có nghiệm \(x=\frac{-1}{3}\)
\(ĐKXĐ:x\ne-4;x\ne\frac{1}{2}\)
\(1+\frac{2x}{x+4}+\frac{27}{2x^2+7x-4}=\frac{6}{2x-1}\)
\(\Leftrightarrow\frac{\left(x+4\right)\left(2x-1\right)}{\left(x+4\right)\left(2x-1\right)}+\frac{2x\left(2x-1\right)}{\left(x+4\right)\left(2x-1\right)}+\frac{27}{\left(x+4\right)\left(2x-1\right)}-\frac{6\left(x+4\right)}{\left(x+4\right)\left(2x-1\right)}=0\)
\(\Leftrightarrow\frac{2x^2+7x-4+4x^2-2x+27-6x-24}{\left(x+4\right)\left(2x-1\right)}=0\)
\(\Leftrightarrow6x^2-x-1=0\)
\(\Leftrightarrow\left(2x-1\right)\left(3x+1\right)=0\)
\(\Leftrightarrow x=-\frac{1}{3}\)
\(\frac{2x-1}{3}=\frac{-27}{1-2x}\)
\(\Rightarrow\left(2x-1\right)\left(1-2x\right)=\left(-27\right).3\)
\(\Rightarrow2x-4x^2-1-2x=-81\)
\(\Rightarrow4x^2-1=-81\)
\(\Rightarrow4x^2=-81+1\)
\(\Rightarrow4x^2=-80\)
Vì \(x^2\ge0\)mà \(4x^2=-80\)
\(\Rightarrow x\in\theta\)
tíc mình nha