Answer: C) 25
Take half of the x coefficient 10 to get 10/2 = 5, then square that result to get 5^2 = 25
This is what you add to both sides
Doing so will have x^2+10x+25 factor to (x+5)^2 on the left side, which completes the square. On the right side, the 8 turns into 33
The steps look like this
x^2+10x = 8
x^2+10x+25 = 8+25 ... adding 25 to both sides
(x+5)^2 = 33 ... factoring
From here you would apply the square root property and subtract 5 from both sides.
