<s>[INST] Solve: $\sqrt{x + 3 + \sqrt{x + 14}} + \sqrt{x+3 - \sqrt{x + 14}} =4 $ I tried:
$\sqrt{x +14} = t$
$\implies \sqrt{x+3 + t} + \sqrt{x+3 - t} = 4$
But I think it is the hard way. Any ideas?
 [/INST] after squaring we get
$$x+3+\sqrt{x+14}+x+3-\sqrt{x+14}+2\sqrt{(x+3)^2-(x+4)}=16$$
simplifying we obtain
$$\sqrt{(x+3)^2-(x+14)}=5-x$$
squaring again
$$(x+3)^2-(x+14)=25+x^2-10x$$
Can you finish?
</s>