Let f=r r be defined by x+y, if x and y are rational fx, y)= 0 otherwise then, (a) f is not continuous at (0, 0) (6y f is continuous at (0, 0) as well as differ

Let f=R R be defined by x+y, if x and y are rational fx, y)= 0 otherwise Then, (a) f is not continuous at (0, 0) (6Y f is continuous at (0, 0) as well as differentiable at (0, 0) (c) fis differentiable only at (0, 0) (d) f is differentiahle evenoachera