Estimating a limit at a point discontinuity from a table of values
Consider the function Note that is defined differently right at than it is everywhere nearby.
The table below shows values of for close to , approaching from both sides.
| 1.9 | 1.99 | 1.999 | 2 | 2.001 | 2.01 | 2.1 | |
|---|---|---|---|---|---|---|---|
| 6.7 | 6.97 | 6.997 | 10 | 7.003 | 7.03 | 7.3 |
Using this table, determine . In your answer, also state whether this limit is equal to .
Hint
Focus only on the values of for near but not equal to — ignore the middle column showing itself, since the limit only cares about nearby behavior.
Step-by-step solution
Looking at the table, as approaches from the left (values ), approaches from below (). As approaches from the right (values ), also approaches , this time from above (). Since both one-sided trends converge to the same number, the two-sided limit exists and equals .
The actual value is irrelevant to the limit computation, since the limit depends only on values of near , not at . Therefore , while , so the limit does not equal the function value at that point — this reflects a removable (point) discontinuity.
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