Math 22 Limits

The Limit of a Function

 Definition of the Limit of a Function
 If $f(x)$ becomes arbitrarily close to a single number $L$ as $x$ approaches $c$ from either side, then
 $\lim _{x\to c}f(x)=L$
 which is read as "the limit of $f(x)$ as $x$ approaches $c$ is $L$

Note: Many times the limit of $f(x)$ as $x$ approaches $c$ is simply $f(c)$, so limit can be evaluate by direct substitution as $\lim _{x\to c}f(x)=f(c)$

Properties of Limits

Let $b$ and $c$ be real numbers, let $n$ be a positive integer, and let $f$ and $g$ be functions with the following limits $\lim _{x\to c}f(x)=L$ and $\lim _{x\to c}g(x)=K$. Then

1. Scalar multiple: $\lim _{x\to c}[bf(x)]=bL$

2. Sum or difference: $\lim _{x\to c}[f(x)\pm g(x)]=L\pm K$

3. Product: $\lim _{x\to c}[f(x)\cdot g(x)]=L\cdot K$

4. Quotient: $\lim _{x\to c}{\frac {f(x)}{g(x)}}={\frac {L}{K}}$

5. Power: $\lim _{x\to c}[f(x)]^{n}=L^{n}$

6. Radical: $\lim _{x\to c}{\sqrt[{n}]{f(x)}}={\sqrt[{n}]{L}}$

Techniques for Evaluating Limits

1. Direct Substitution

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