For each of the following functions, find the maximum and minimum values of the function on the circular disk: $x^{2} + y^{2} \leq 1$. Do this by looking at the level curves and gradients.

(A) $f(x, y) = x + y + 1$:
maximum value =
minimum value =

(B) $f(x, y) = 1 x^{2} + 2 y^{2}$:
maximum value =
minimum value =

(C) $f(x, y) = 1 x^{2} - 2 y^{2}$:
maximum value =
minimum value =