# At a Glance - Continuity on an Interval via Pictures

Remember, f is continuous on an interval if we can finger paint over f on that interval without lifting our drawing digit.

### Sample Problem

Look at the function f drawn below:

1.  The function f is continuous on the interval (-5,5) because if c is any point in (-5,5),  . We can start our pencil out on the graph at x = -5 and trace the graph to x = 5 without lifting the pencil.
2.  This function is not continuous on the interval (5,8) because f is not continuous at x = 7. When x = 7 we need to lift the pencil to trace the graph.
3. Here's a tricky one: the function f is continuous on the interval (5,7). The only point on the whole graph at which f is discontinuous is x = 7, and 7 isn't in the interval (5,7).

#### Exercise 1

Look at the function f drawn below:

Determine whether the function is continuous on the given interval. If not, state the points in the interval at which f is discontinuous.

• (-5,-3)

#### Exercise 2

Determine whether the function is continuous on the given interval. If not, state the points in the interval at which f is discontinuous.

•  (-5,3)

#### Exercise 3

Determine whether the function is continuous on the given interval. If not, state the points in the interval at which f is discontinuous.

• (9,10)

#### Exercise 4

Determine whether the function is continuous on the given interval. If not, state the points in the interval at which f is discontinuous.

• (-3,-1)

#### Exercise 5

Determine whether the function is continuous on the given interval. If not, state the points in the interval at which f is discontinuous.

• (0,4)