I need help solving this equation.

3√z+1=-3

How do I do this problem? Thanks for your help.

3√z+1 = -3

3√z = -4
Now, √z is interpreted to be positive
√4 = 2, not ±2
so, there is no solution to the equation
3√z = -4
since √z is positive

However, we can go on to say that

3√z = -4
9z = 16
z = 16/9

But, this is really a spurious solution, since

3√(16/9)+1 = 3(4/3)+1 = 4+1 = 5
We cannot use -4/3 as √(16/9) unless specifically indicated.