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Notes 2.1 - Limits. I. Limit Notation. A.) Two-sided Notation: Read as “the limit of f ( x ) as x approaches a is L .”. B.) One-sided Notation: Read as “the limit of f ( x ) as x approaches a from the right is L .”
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I. Limit Notation A.) Two-sided Notation: Read as “the limit of f(x) as x approaches a is L.”
B.) One-sided Notation: Read as “the limit of f(x) as x approaches a from the right is L.” Read as “the limit of f(x) as x approaches a from the left is L.”
II. Limit Definition A.) Def: The function f has a limit L as x approaches ciff: B.) Visual Representations:
III. Non-existent Limits A.) fails to existwhen: 1.) The right-side limit and left-side limit equal different real numbers. 2.) The are infinite oscillations . 3.) The limit(s) approach
Ex. – Evaluate Although limits approaching infinity do not exist, we must still describe the behavior from both/each side(s)!!!
IV. Computational Techniques for Limits A.) Properties of Limits: p. 61-62 of your text. KNOW THEM!!! SUM, DIFFERENCE, PRODUCT, CONSTANT MULTIPLE, QUOTIENT, and POWER RULES
C.) Limit Properties and Theorems valid for one-sided limits as well.
V. Techniques for Evaluation A.) Apply the theorems/properties (Substitute) B.) Modify the expression: 1.) Simplify 2.) Factor 3.) Expand 4.) Multiply by conjugates 5.) Apply thm./prop. again
3.) 4.)
VI. You Try! 1.) 2.) 3.) 4.)
VII. Sandwich Theorem GRAPHICALLY
B.) Example - What do you know about the sin function?
IX. Proof of Given the point P in the first quadrant on the unit circle: The area of sector OAP = P (x, y) 1 O (0, 0) 𝜃 A (1, 0)
Dropping a perp. From P to Q on the x-axis gives us triangle OPQ The area of triangle OPQ = P (x, y) 1 𝜃 O (0, 0) Q (x,0) A (1, 0)
Now, we can all agree that P (x, y) 1 𝜃 O (0, 0) Q (x,0) A (1, 0)
Extending OP to T and dropping a perp. from T to A on the x-axis gives us triangle OTA The area of triangle OTA = T(1, tan 𝜃) P 1 𝜃 O (0, 0) A Q
Now, we can all agree that T(1, tan 𝜃) P 1 𝜃 O (0, 0) A Q
X. Patching In order to make our trigonometric limits look like A-D of II, we may need to “PATCH” the trig expression. After, we apply our limit properties and verify on our calculator. A) Examples -