giai ho mk vs
\(A=\frac{6x^2+8x+7}{x^3-1}+\frac{x}{x^2+x+1}+\frac{6}{1-x}\)
\(\Leftrightarrow A=\frac{6x^2+8x+7}{x^3-1}+\frac{x\left(x-1\right)}{x^3-1}+\frac{-6\left(x^2+x+1\right)}{x^3-1}\)
\(\Leftrightarrow A=\frac{6x^2+8x+7+x^2-x-6x^2-6x+1}{x^3-1}\)
\(\Leftrightarrow A=\frac{x^2+x+1}{x^3-1}=\frac{1}{x-1}\)
\(4A=x-1\)
\(\Leftrightarrow4.\left(\frac{1}{x-1}\right)=x-1\)
\(\Leftrightarrow\left(\frac{4}{x-1}\right)-\frac{\left(x-1\right)\left(x-1\right)}{x-1}=0\)
\(\Leftrightarrow\left(\frac{4-\left(x-1\right)^2}{x-1}\right)=0\)
\(\Leftrightarrow4-\left(x-1\right)^2=0\)
\(\Leftrightarrow-\left(x-1\right)^2=-4\)
\(\Leftrightarrow\left(x-1\right)^2=4\)
\(\Leftrightarrow x-1=\pm2\)
x-1=2=>x=3(Loại vì x<0, đề cho)
x-1=-2=>x=-1
ai giai ho mk vs
