1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our...

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Can you draw an example of a function that: 1)Is defined everywhere, but does not have a limit at 2)Is not defined at , but does have a limit there 3)Has a limit at x=c that is not the same value as

Transcript of 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our...

Page 1: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

Can you draw an example of a function that:

1) Is defined everywhere, but does not have a limit at

2) Is not defined at , but does have a limit there

3) Has a limit at x=c that is not the same value as

Page 2: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

1.3: Evaluating Limits Analytically

Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

Page 3: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

Properties of Limits

See Theorem 1.1 and 1.2

Page 4: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

1. Limits of Polynomials lim ( ) ( )x c

p x p c

2

3Ex: lim 2 5

xx x

1) Try direct substitution first, if real number then done!

Page 5: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

1. Limits of Rational Functions

2 2 8( )

2

x xf x

x

2) If direct substitution fails:

Simplify to find another function that agrees for all x, except x = c

2 2

1

2 8 (1) 2(1) 8 5lim 5

2 1 2 1x

x x

x

lim𝑥→1

𝑓 (𝑥)Find:

Page 6: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

Evaluate the following limits.2

24

5 41) lim

2 8x

x x

x x

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3

1 22) lim

3x

x

x

Page 8: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

0

1 14 43) lim

x

xx

Page 9: 1.3: Evaluating Limits Analytically Limitations live only in our minds. But if we use our imaginations, our possibilities become limitless.

Summary – to find limits analytically

1) Try direct substitution

2) Simplify to a single fraction

3) Try factoring/cancel terms

4) Multiply by conjugate

Note: If none of these work, a graph or numerical investigation may give you insight into whether the limit exists at all (recall the 3 cases!)