a, ĐKXĐ: 9\(x^2\) - 6x + 1 \(\ne\) 0

\(\Leftrightarrow\) \(\left(3x-1\right)^2\)\(\ne\) 0

\(\Leftrightarrow\) x \(\ne\) \(\dfrac{1}{3}\)

b,Thay x = -8( thỏa mãn ĐKXĐ) vào phân thức C ta có:

C = \(\dfrac{3\left(-8\right)^2-\left(-8\right)}{9\left(-8\right)^2-6\left(-8\right)+1}\)

\(\Leftrightarrow\) C = \(\dfrac{200}{625}\)

\(\Leftrightarrow\) C = \(\dfrac{8}{25}\)

c,Ta có:

C = \(\dfrac{3x^2-x}{9x^2-6x+1}=\dfrac{x\left(3x-1\right)}{\left(3x-1\right)^2}=\dfrac{x}{3x-1}\)