We have a piecewise function.
Therefore, to find the function, we must evaluate each domain separately.
We have then:
For
:
The function for this domain is:

For
:
The function for this domain is:

Where,

Substituting:

For
:
The function for this domain is:
This is not a solution. When plugged in,
8 > 20 + 4.
8 > 24, which is not true. :)
The one and the negative one
Number 7 is C, im not sure about 6 though