Use a table of functional values to evaluate lim x → 2 | x 2 − 4 | x − 2, lim x → 2 | x 2 − 4 | x − 2, if possible. We apply this Problem-Solving Strategy to compute a limit in Example 2.4. We may need to zoom in on our graph and repeat this process several times. If the y-values approach L as our x-values approach a from both directions, then lim x → a f ( x ) = L. We can use the trace feature to move along the graph of the function and watch the y-value readout as the x-values approach a. Using a graphing calculator or computer software that allows us to graph functions, we can plot the function f ( x ), f ( x ), making sure the functional values of f ( x ) f ( x ) for x-values near a are in our window.We can use the following strategy to confirm the result obtained from the table or as an alternative method for estimating a limit. If both columns approach a common y-value L, we state lim x → a f ( x ) = L.( Note: Although we have chosen the x-values a ± 0.1, a ± 0.01, a ± 0.001, a ± 0.0001, a ± 0.1, a ± 0.01, a ± 0.001, a ± 0.0001, and so forth, and these values will probably work nearly every time, on very rare occasions we may need to modify our choices.) In our columns, we look at the sequence f ( a − 0.1 ), f ( a − 0.01 ), f ( a − 0.001 ). Next, let’s look at the values in each of the f ( x ) f ( x ) columns and determine whether the values seem to be approaching a single value as we move down each column.Table 2.1 Table of Functional Values for lim x → a f ( x ) lim x → a f ( x ) We begin our exploration of limits by taking a look at the graphs of the functions At the end of this chapter, armed with a conceptual understanding of limits, we examine the formal definition of a limit. We therefore begin our quest to understand limits, as our mathematical ancestors did, by using an intuitive approach. Yet, the formal definition of a limit-as we know and understand it today-did not appear until the late 19th century. In fact, early mathematicians used a limiting process to obtain better and better approximations of areas of circles. The concept of a limit or limiting process, essential to the understanding of calculus, has been around for thousands of years. 2.2.6 Using correct notation, describe an infinite limit.2.2.5 Explain the relationship between one-sided and two-sided limits.2.2.4 Define one-sided limits and provide examples.2.2.3 Use a graph to estimate the limit of a function or to identify when the limit does not exist.2.2.2 Use a table of values to estimate the limit of a function or to identify when the limit does not exist.2.2.1 Using correct notation, describe the limit of a function.
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