(a)

Theorem :

If is a continuous function at , then , where is a constant.

The limit of the function is .

Definition of continuity :

The function is a continuous at , then .

.

(b)

Theorem :

If and  are continuous function at , then .

The limit of the function is .

Definition of continuity :

The functions and is a continuous at , then and .

.

(a) .

(b) .