[tex] \sqrt{x} + \sqrt{x+3}=3|()^2 \Rightarrow x+2 \sqrt{x(x+3)}+x+3=9 \Rightarrow \\ \Rightarrow 2x+2 \sqrt{ x^{2} +3x}=6 \Rightarrow 2 \sqrt{ x^{2} +3x}=6-2x|()^2 \Rightarrow \\ \Rightarrow 4( x^{2} +3x) = 36 - 24x+4 x^{2} \Rightarrow4 x^{2} - 4x^{2} +12x +24x =36 \Rightarrow \\ 36x = 36 \Rightarrow x = 1 [/tex]
