Your pre-calculus teacher will tell you that three things have to be true for a function to be continuous at some value c in its domain:
- f(c) must be defined. ...
- The limit of the function as x approaches the value c must exist. ...
- The function's value at c and the limit as x approaches c must be the same.
How do you show that a function is continuous?
Saying a function f is continuous when x=c is the same as saying that the function's two-side limit at x=c exists and is equal to f(c).
How do you prove a function is continuous example?
To prove that f is continuous at 0, we note that if 0 ≤ x<δ where δ = ϵ2 > 0, then |f(x) − f(0)| = √ x < ϵ. f(x) = ( 1/x if x ̸= 0, 0 if x = 0, is not continuous at 0 since limx→0 f(x) does not exist (see Example 2.7).