Question

\(\sqrt{9x+9\:}\) +\(\sqrt{4x+4}\) =\(\sqrt{X+1}\)

Answer 1

\(\sqrt{9x+9}+\sqrt{4x+4}=\sqrt{x+1}\)ĐK : \(x\ge-1\)

\(\Leftrightarrow3\sqrt{x+1}+2\sqrt{x+1}=\sqrt{x+1}\)

\(\Leftrightarrow4\sqrt{x+1}=0\)

\(\Leftrightarrow\sqrt{x+1}=0\)

\(\Leftrightarrow x=-1\)

Vậy....

Answer 2

ĐK : \(x\ge-1\)

Đặt \(t=\sqrt{x+1}\ge0\) thì pt đã cho trở thành :

\(3t+2t=t\)

\(\Leftrightarrow4t=0\Leftrightarrow t=0\)

\(\Leftrightarrow\sqrt{x+1}=0\Leftrightarrow x=-1\) ( TM )