2 min readβ’june 7, 2020

Anusha Tekumulla

Using tables to estimate limit values helps us better visualize what a limit actually is. In order to understand this concept, letβs look at an example.Β π

The easiest way to find a limit is to plug in the given x value into the function. However, youβll find that the given function isnβt defined at x = 3 because the denominator evaluates to 0. Because we canβt find the function value at x = 3, we find the limit by approaching x = 3.Β

1) We have to make a table and the first step is picking the x values to use. Pick a value that's a little bit less than x = 3 (that is, a value that's "to the left" π of 3), so maybe start with something like x = 2.9.

x | 2.9 | 3 |

f(x) | 0.16949 | undefined |

2) Next, add a couple more x-values to your table to simulate the feeling of getting infinitely close to x = 3, from the left.

x | 2.9 | 2.99 | 2.999 | 3 |

f(x) | 0.16949 | 0.16694 | 0.16669 | undefined |

3) Approach x = 3 from the right just like we did from the left.Β

x | 2.9 | 2.99 | 2.999 | 3 | 3.001 | 3.01 | 3.1 |

f(x) | 0.16949 | 0.16694 | 0.16669 | undefined | 0.16664 | 0.16639 | 0.16393 |

Now that we have our table, we can estimate the limit of f(x) = x - 3 β x^2 - 9 at x = 3 is **0.1667 **or **1 β 6**.Β

It is important to pick x values that get infinitely close to the target value. In the example above, we picked numbers that were closer and closer to x = 3. We wouldnβt be able to estimate the limit value if we used numbers with equal increments like 2.25, 2.5, and 2.75.Β

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