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Estimating Limit Values from Tables

Samuel Baker

Samuel Baker

7 min read

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Study Guide Overview

This study guide covers estimating limits from tables, focusing on the concept of a limit, particularly one-sided limits. It explains how to use tables to estimate limits when direct substitution fails, including choosing appropriate x-values and interpreting the resulting y-values. The guide provides practice questions and emphasizes the importance of checking if left-hand and right-hand limits are equal for the limit to exist.

AP Calculus AB/BC: Estimating Limits from Tables 📈

Welcome to your ultimate guide for mastering limits using tables! This guide is designed to be your go-to resource, especially the night before the exam. Let's make sure you're confident and ready to ace it!

Key Concept

Remember, a limit is the value a function approaches as the input (x) gets closer to a specific value. It's all about what's happening near a point, not necessarily at the point.

Concept of a Limit Recap

As we've discussed, a limit describes the behavior of a function as its input approaches a certain value. The notation looks like this:

limxaf(x)=L\lim_{x \to a} f(x) = L

Here, 'x' approaches 'a', and 'L' is the limit. We're diving into how to find 'L' using tables. 🔢

One-Sided Limits

Before we jump into tables, it's crucial to understand one-sided limits. These look at the function's behavior as 'x' approaches 'a' from either the left (values less than 'a') or the right (values greater than 'a').

  • Approaching from the right (values greater than 'a'): limxa+f(x)=L\lim_{x \to a^+} f(x) = L
  • Approaching from the left (values less than 'a'): limxaf(x)=L\lim_{x \to a^-} f(x) = L

Think of it like approaching a destination from different directions. ⬅️➡️

Memory Aid

Remember: a+ means approach from the right (positive side), and a- means approach from the left (negative side).


Using a Table to Estimate Limits

Sometimes, direct substitution doesn't work (we get an indeterminate form like 00\frac{0}{0}). In these cases, we use a table to see what happens as 'x' gets close to 'a'. ❌

For example:

limx0xx+11\lim_{x \to 0} \frac{x}{\sqrt{x+1}-1}

Direct substitution gives us 00\frac{0}{0}, which is und...

Question 1 of 9

What does the notation limxaf(x)=L\lim_{x \to a} f(x) = L represent? 🤔

The value of the function at x=a

The slope of the function at x=a

The value that f(x) approaches as x gets closer to a

The y-intercept of the function