c.\(\dfrac{5x+4}{3}-1=\dfrac{3x-2}{4}\)
\(\Leftrightarrow\dfrac{4\left(5x+4\right)-12}{12}=\dfrac{3\left(3x-2\right)}{12}\)
\(\Leftrightarrow4\left(5x+4\right)-12=3\left(3x-2\right)\)
\(\Leftrightarrow20x+16-12=9x-6\)
\(\Leftrightarrow11x=-10\)
\(\Leftrightarrow x=-\dfrac{10}{11}\)
d.\(ĐK:x\ne\pm1\)
\(\Rightarrow\dfrac{x+1}{x-1}-\dfrac{x-1}{x+1}=\dfrac{4x}{\left(x-1\right)\left(x+1\right)}\)
\(\Leftrightarrow\dfrac{\left(x+1\right)\left(x+1\right)-\left(x-1\right)\left(x-1\right)}{\left(x-1\right)\left(x+1\right)}=\dfrac{4x}{\left(x-1\right)\left(x+1\right)}\)
\(\Leftrightarrow\left(x+1\right)^2-\left(x-1\right)^2=4x\)
\(\Leftrightarrow x^2+2x+1-x^2+2x-1-4x=0\)
\(\Leftrightarrow0=0\left(đúng\right)\)
Vậy \(x=R\)
