Left-hand limit from a table of values
Consider the piecewise function We want to investigate the behavior of as approaches .
Build a table of values of for (values approaching from the left, using the rule since these values are less than ). Based on the trend in your table, what value does appear to approach as ? That is, estimate
Hint
Since each of these -values is less than 1, use the rule to compute the outputs, then observe what value they seem to be getting closer to.
Step-by-step solution
For slightly less than , we use the branch . Computing values: , , , and . These outputs are clearly getting closer and closer to as gets closer to from below.
Since the outputs approach as approaches from the left, we conclude . Note this is true even though itself is computed using the other branch — the limit only depends on values near , not at .
Right-hand limit from a table of values
Now build a table of values of for (values approaching from the right, using the rule since these values are at least ). Based on the trend in your table, estimate
Hint
For these -values, , so use the rule to compute the outputs, then see what value they approach.
Step-by-step solution
For slightly greater than , we use the branch . Computing values: , , , and . These outputs steadily decrease toward as approaches from above.
Since the outputs approach as , we conclude .
Existence of the two-sided limit
Using your conclusions from the left-hand and right-hand limits, does exist? If it exists, state its value.
Hint
Recall that a two-sided limit exists exactly when both one-sided limits exist and agree with each other.
Step-by-step solution
From part (a), , and from part (b), . Since both one-sided limits exist and are equal to the same value, the two-sided limit exists.
Therefore . Note that this value happens to match as well, but that agreement is not required for the limit to exist — only the one-sided limits needed to match each other.
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