Determine whether the following operators are linear or nonlinear. a) A^f(x)=SQUARE f(x) b) A^f(x)=f *(x) (Hint: form the complex conjugate of f(x)) c) A^f(x)=0 (multiply f(x) by zero d) A^f(x)=[f(x)]-1 (take the reciprocal of f(x)) e) A^f(x)=f(0) (evaluate f(x) at x=0) f) A^f(x)=ln f(x) (take the logarithm of f(x))