Question

3 sqrt x+4 + 3 sqrt 2x+8=0

Answer 1

$3\sqrt{x+4}+3\sqrt{2x+8}=0$

Subtract $3\sqrt{2x+8}$ from both sides.

$3\sqrt{x+4}= -3\sqrt{2x+8}$

Square and expand both sides.

9x+36=18x+72

Subtract 9x from both sides.

36=9x+72

Subtract 72 from both sides.

-36=9x

Divide both sides by 9.

-4=x

Your answer would be -4.

I hope this helps :)