\(a,\left(2x-1\right)^2-25=0.\\ \Leftrightarrow\left(2x-1\right)^2=25.\\ \Leftrightarrow\left[{}\begin{matrix}2x-1=5.\\2x-1=-5.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3.\\x=-2.\end{matrix}\right.\)
\(b,\left(x-3\right)\left(5-2x\right)=0.\\ \Leftrightarrow\left[{}\begin{matrix}x-3=0.\\5-2x=0.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3.\\x=\dfrac{5}{2}.\end{matrix}\right.\)
\(c,\dfrac{x+1}{x-2}+\dfrac{x-1}{x+2}-\dfrac{2\left(x^2+2\right)}{x^2-4}=0.\)
\(\left(x\ne\pm2\right).\)
\(\Leftrightarrow\dfrac{\left(x+1\right)\left(x+2\right)+\left(x-1\right)\left(x-2\right)-2x^2-4}{\left(x-2\right)\left(x+2\right)}=0.\)
\(\Rightarrow\left(x+1\right)\left(x+2\right)+\left(x-1\right)\left(x-2\right)-2x^2-4=0.\)
\(\Leftrightarrow x^2+3x+2+x^2-3x+2-2x^2-4=0.\)
\(\Leftrightarrow0=0\) (luôn đúng).
