As, f(x) is continuous and g(x) is discontinuous.
Case I g(x) is discontinuous as limit does not exist at x = k.
`:." " phi(x) = f(x) + g(x)`.
`rArr underset( x to k) lim phi (x) = underset( x to k) lim {f(x)+g(x)} ` = does not exist.
` :. phi (x) ` is discontinuous.
Case II g(x) is discontinuous as, ` underset (x to k) lim g(x) ne g(k)`.
`:." " phi(x) = f(x) + g(x)`.
` rArr underset ( x to k) lim { f(x) + g(x)} ` exists and is a finite quantity
but ` phi(k) = g(k) ne underset( x to k) lim {f(x)+g(x)}`
`:." " phi (x) = f(x) + g(x) ` is discontinuous,
whenever g(x) is discontinuous.
