Question 472224
Since a^2 is always nonnegative, for large-magnitude values of a, 4 - a^2 will decrease the value of b. To find the maximum value for b, we find the minimal value of a^2, which occurs when a = 0. This implies the maximum value of b is 4.


To minimize b, we maximize a^2 by setting a = -3 (the number contained in the domain with the highest absolute value). The least possible value of b is 4 - (-3)^2 = -5.


Hence the difference between the two is 4 - (-5) = 9.