Please I need someone very smart to explain this open ended this is algebra 2

No.  The correct answer is x = 4i.  The mistake is made on the penultimate step where "Mark" squares both sides, eliminating the negative sign.

Step-by-step explanation:

We can see that the answer is incorrect, because if we plug it back into the original equation, we get:

This of course is obviously incorrect.  The mistake is made in squaring away the negative sign in solving the problem.  An easier way to look at this is to get rid of √x, and substitute it for "n", and see what we get:

If we swap √x back in, we get:

√x = -2

x = 4i

let's solve it correctly:

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8