Calculus: Continuity by: javier

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Calculus: Continuity

by: javier

Review Limits: Methods to determine

Review: Limits: Methods to determine

□ Plug-in-Method [PIM] □ Engeneer’s Method [EM] □ Graphs □ Re-Write [RW] □ Recognize Famous limits

Review: Limits: Methods to determine

□ Plug-in-Method [PIM]

( ) lim x3 + 2

x→3

□ Engeneer’s Method [EM] □ Graphs □ Re-Write [RW] □ Recognize Famous limits

Review: Limits: Methods to determine

□ Plug-in-Method [PIM] □ Engeneer’s Method [EM]

lim ln(x) − ln(5)x − 5

x→5

□ Graphs □ Re-Write [RW] □ Recognize Famous limits

Review: Limits: Methods to determine □ Plug-in-Method [PIM] □ Engeneer’s Method [EM] □ Graphs 1

0.5

0

−0.5

∞ 0

10

□ Re-Write [RW] □ Recognize Famous limits

20

30



Review: Limits: Methods to determine

□ Plug-in-Method [PIM] □ Engeneer’s Method [EM] □ Graphs □ Re-Write [RW] □ Recognize Famous limits

lim xx

x→0+

Review Limits: Definitions

Review: Limits: Definitions

□ (lim at c) □ (lim at infinity)

Review: Limits: Definitions

□ (lim at c) lim f(x) = L ⇐⇒ ∀ϵ > 0 ∃ δ > 0 ∋ 0|x − c| < δ =⇒ |f(x) − L| < ϵ

x→c

□ (lim at infinity)

Review: Limits: Definitions

□ (lim at c) lim f(x) = L ⇐⇒ ∀ϵ > 0 ∃ δ > 0 ∋ 0|x − c| < δ =⇒ |f(x) − L| < ϵ

x→c

□ (lim at infinity) lim f(x) = L ⇐⇒ ∀ϵ > 0 ∃ M ∋ x > M =⇒ |f(x) − L| < ϵ

x→∞

Review Limits: properties

Review: Limits: properties

□ (lim of k)

limx→c k = k

□ (lim of x)

limx→c x = c

□ (pull k)

limx→c kf(x) = k limx→c f(x)



(LS=SL)∗

limx→c (g(x) + f(x)) = limx→c g(x) + limx→c f(x)



(LP=PL)∗

limx→c (g(x) · f(x)) = limx→c g(x) · limx→c f(x)

□ (LQ=QL)∗

limx→c

g(x) f(x)

=

limx→c g(x) limx→c f(x)

Review: Limits: properties

□ (lim of k)

limx→c k = k

□ (lim of x)

limx→c x = c

□ (pull k)

limx→c kf(x) = k limx→c f(x)



(LS=SL)∗

limx→c (g(x) + f(x)) = limx→c g(x) + limx→c f(x)



(LP=PL)∗

limx→c (g(x) · f(x)) = limx→c g(x) · limx→c f(x)

□ (LQ=QL)∗

limx→c

g(x) f(x)

∗ each must exists and be finite

=

limx→c g(x) limx→c f(x)

Review Limits: Reason for being

Review: Limits: Reason for being

□ We need limits to evaluate and make sense of indeterminate forms. □ We need to evaluate indeterminate forms to compute areas, infinite many , each infitely small... and ... □ (also) We need to evaluate indeterminate forms to compute slopes, infinitely small rise over infinitely small

runs. □ We need to compute areas and slopes because when a meaninful label is put on the x and the y coordinates the area/slope represents something meaningful, many real life science quesions are solved gracefully this way.

Review: Limits: Reason for being

□ We need limits to evaluate and make sense of indeterminate forms. ∞ · 0, 00 etc □ We need to evaluate indeterminate forms to compute areas, infinite many , each infitely small... and ... □ (also) We need to evaluate indeterminate forms to compute slopes, infinitely small rise over infinitely small

runs. □ We need to compute areas and slopes because when a meaninful label is put on the x and the y coordinates the area/slope represents something meaningful, many real life science quesions are solved gracefully this way.

Continuity layman definition

Continuity: layman definition

Is this function continous at x = 2 ? □ Can we ’trace’ the graph around x = 2 □ without lifting our pencil □ without running out of ink

6

4

2

0 −4

−2

0

2

4

Continuity: layman definition

Is this function continous at x = 0 ? □ Can we ’trace’ the graph around x = 0 □ without lifting our pencil □ without running out of ink

6

4

2

0 −4

−2

0

2

4

Continuity: layman definition

Is this function continous at x = 0 ? □ Can we ’trace’ the graph around x = 0 □ without lifting our pencil □ without running out of ink

4 3 2 1 0 −4

−2

0

2

4

Continuity: layman definition

Is this function continous at x = 0 ? □ Can we ’trace’ the graph around x = 0 □ without lifting our pencil □ without running out of ink

4 3 2 1 0 −1 −4

−2

0

2

4

Continuity: layman definition

Y

Is this function continous at x = 0 ? □ Can we ’trace’ the graph around x = 0 □ without lifting our pencil □ without running out of ink

y = tan(x)

X

Continuity: layman definition

Is this function continous at x = π2 ? □ Can we ’trace’ the graph around x = □ without lifting our pencil □ without running out of ink

Y

y = tan(x)

X

π 2

Continuity: layman definition

Is this function continous at x = 0 ? □ Can we ’trace’ the graph around x = 0 □ without lifting our pencil □ without running out of ink

1 0.5 0 −0.5 f(x) = sin

−1 −0.5

0

0.5

(1) x

1

Continuity rigorous definition

Continuity: rigorous definition

DEFINITION: f(x) is said to be ”continous at c” IFF? □ limx→c f(x) exists and is finite □ f(c) exists and is finite □ the above two are equal

10

5 f(x) 0

−1

0

1

2

Continuity what can you do with it

Continuity: what can you do with it

DEFINITION: f(x) is said to be ”continous at c” IFF? □ many nice things happen when for continous functions □ continous functions make continous functions when added, multiplied, etc □ continous functions allow limits through

Continuity: what can you do with it

DEFINITION: f(x) is said to be ”continous at c” IFF? □ many nice things happen when for continous functions □ continous functions make continous functions when added, multiplied, etc □ continous functions allow limits through √ √ limx→3 x + 1 = limx→3 x + 1

Continuity: what can you do with it

DEFINITION: f(x) is said to be ”continous at c” IFF? □ many nice things happen when for continous functions □ continous functions make continous functions when added, multiplied, etc □ continous functions allow limits through √ √ limx→3 x + 1 = limx→3 x + 1 √ √ limx→−5 x + 1 = limx→−5 x + 1

Continuity famous types of discontinuities

Continuity: famous types of discontinuities

DEFINITION: f(x) is said to be ”continous at c” IFF? □ JUMP Discontinuities □ ASYMPTOTE Discontinuities □ REMOVABLE Discontinuities □ OTHER Discontinuities

Continuity famously continous everywhere functions

Continuity: famously continous everywhere functions

some functions that are fmaously continous at every real number: □ polynomials □ sin(x) and cos(x) □ exponential functions, ex □ combinations of these