The domain is

The general procedure with such a type of equation is:

Square both sides - isolate remaining roots at one side - square again - isolate ... and so on:

...... Square again:

...... Collect like terms:

I don't know how to solve such an equation algebraically. So I used my computer which calculated 4 approximate solutions:

Since squaring is not an equivalent operation you must check these values by plugging them into the original equation and check if they satisfy the equation.

Better use a calculator