Question

giải phương trình 

a) x - \(\sqrt{x-1}\) -3 = 0

b)\(\sqrt{4x^2+8x+4}\) = x - 3

c) 2x + 5 +\(2\sqrt{2x+5}\) = 13

Answer 1

Answer 2

Answer 3

Answer 4

b) Ta có: \(\sqrt{4x^2+8x+4}=x-3\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=-5\left(loại\right)\\3x=1\end{matrix}\right.\Leftrightarrow x=\dfrac{1}{3}\left(loại\right)\)