Please answer number 8

Step-by-step explanation:

I missed the x >= 0.

therefore only positive x (and then renamed y) are possible for the reverse function

that is easy and quick.

y = x² + 2

y - 2 = x²

x = +sqrt(y - 2)

and after trading the variable names to a regular function definition we then have

y = +sqrt(x - 2)

so, D is the right answer.