Negative numbers. Remember that whole numbers are 0 and positive numbers.
The answer is 0.314 radian
The pattern is:
( a - b )² = a² - 2 a b + b² ( square of last term of binomial - the missing term)
x² - 2 · 8 · x + 8² = x² - 16 x + 64 = ( x - 8 )²
The missing term is: 64