8 - sqrt(3) is indeed the conjugate of 8 + sqrt(3).
What are you asking here? You are to "evaluate or simplify" what?
Answer:

Step-by-step explanation:
A root can be converted to a power by taking the base of the root (in this case 4) and making it 1 over that number, so in this case 
If it were the fifth root you would make it to the 1 over 5 power.
When x = 1
5(1) = -y + 6
5 = -y + 6
y = 6 - 5 = 1
When x = 2
5(2) = -y + 6
10 = -y + 6
y = 6 - 10 = -4
When x = 3
5(3) = -y + 6
15 = -y + 6
y = 6 - 15 = -9
Number 333333333333333333333333