Answer:
-100
Step-by-step explanation:
x^2 - 20x - 25 = 0
In order to complete the square, we need it to follow the a^2 +/- 2ab + b^2 pattern
In this case since the coefficient before x is negative, it is (a-b)^2 = a^2 - 2ab + b^2
a = x
2ab = -20x
xb = -10x
b = -10
(x - 10)^2
Now since (-10)^2 is 100
We have to subtract 100 from our perfect square and subtract 25 since it is part of the original question
(x - 10)^2 - 100 - 25
Basically, you just have to add - 100 to the original equation to complete the square
