**with 2 different eigenvalues**

*L**a1*and

*a2*, with their corresponding eigenfunction

*f1*and

*f2*. Is

*f1 + f2*also an eigenfunction of

**? If so, what eigenvalue of**

*L***does it correspond to? If not, why not?**

*L*b) Answer the same question as in part (a) but for the difference of the 2 functions;

*f1-f2*.