Question

Giai phuong trinh
a) \(\dfrac{x+2}{x+1}+\dfrac{3}{x-2}=\dfrac{3}{x^2-x-2}\)

b)\(\sqrt{1-4x+4x^2}-3=0\)

Answer 1

b , \(\sqrt{1-4x+4x^2}-3=0\)

\(\Leftrightarrow\sqrt{\left(1-2x\right)^2}=3\)

\(\Leftrightarrow\left|1-2x\right|=3\)

\(\Leftrightarrow\left[{}\begin{matrix}1-2x=3\\1-2x=-3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}-2x=2\\-2x=-4\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=2\end{matrix}\right.\)

Vậy nghiệm của phương trình là \(S=\left\{-1,2\right\}\)