Question

Solve:
2y - x + 3 = 0
$y=\sqrt{x}$

Answer 1

$y=\sqrt{x}\Rightarrow x=y^2$

Now, $2y-x+3=0\Rightarrow 2y-y^2+3=0\Rightarrow y^2-2y-3=0$

$y^2-3y+y-3=0\Rightarrow (y+1)(y-3)=0\Rightarrow y=3,-1$

But $y$ cannot be negative because $y=\sqrt{x}$

So, $y=3\Rightarrow \sqrt{x}=3\Rightarrow x=9$