By Gökhan Bilhan 1 Calculus 1 (Week 6)-Limits of Exponential, Logarithmic and Trigonometric Functions Example limx→1 ex x2 −x 2 −x limx→1 e x−1 Example 1 limx→−∞ ex limx→0− e x By looking at the graph of limx→∞ lnx = and Let's look at the graph of Then obviously limx→0 Examples 1-) limx→0 sin2 x = x2 lnx, sinx = x we may say that limx→0 lnx = By Gökhan Bilhan 2 2-) sin2 x limx→0 = x 3-) limh→0 cosh − 1 = h Exercises 1. Find a∈R so that the following limit exists. limx→0 ( x2 + ax ) 1 − cosx 2. limx→0 ( 1 − cos(tanx) ) tanx 3. limx→0 ( sin7x ) tan7x By Gökhan Bilhan 4. sin2 x limx→0 ( ) 1 − secx 5. limx→0 3 sin(sin(sinx)) sin(sinx) Theorem(The Sandwich Theorem) Suppose that g(x) ≤ f (x) ≤ h(x) for all x in some open interc, except limx→c f (x) = L. val containing then possibly at x=c itself. Suppose also that limx→c g(x) = limx→c h(x) = L, Theorem The trigonometric functions y = sinx and y = cosx are continuous everywhere. Denition A function f (x) is called bounded near x0 , if |f (x)| ≤ M x near to (M is real number)for every x0 Theorem If f (x) is bounded near a and if limx→a g(x) = 0 then limx→a f (x).g(x) = 0 Example limx→0 (x.sin 1 ) x Example limx→0 (sinx.sin (Note that 1 ) x |sinx| ≤ 1 and |cosx| ≤ 1 for all x.) By Gökhan Bilhan 4 Example limx→0 sinx(cotx).sinx Example limx→0 tanx.sin 1 x Exercises π limx→π 2 2 2 =? x −π cos 1. 2. limx→1 sinπx =? x2 − 1 3. limx→1 1 πx .cos =? 1−x 2 4. limx→0 sin(sinx) =? x By Gökhan Bilhan 5 5. limx→∞ x2 − x = 6. limx→∞ x2 + x = 3−x By Gökhan Bilhan 6 (Week 5)-Trigonometric and Other Limits(Exercises) Exercises 1. lim π( x→ 3 A)2 2. 3. 4. lim √ √ B) 3 π( x→ 6 3−1 C)0 D)− √ E)−2 3 √ 3−1 B) limx→∞ sin3x =? 3x A)0 B)1 C) C)3 √ 1 (1 − 3) 2 D)4 D) √ A)sin 9 limx→0 tanx − sinx =? sin3 x 1 3 √ 3 (1 + 3) π E)No limit √ limx→−π sin 10 + cosx =? A) 2 √ sinx + cosx ) =? π −x 3 A)0 √ 5. 2sinx − tanx ) =? cosx B)1 B)cos C)0 9 C)0 3 D) 2 D)1 E)2 E)sin9 E) π 3 By Gökhan Bilhan 6. π cos( x) 2 limx→1 =? sinπx A) 7. 7 − 12 lima→x A)1 B)− 4 1 C)0 1 D) 4 1 E) 2 x2 − a2 =? sin(2x − 2a) B)x C)a D)2a E) x 2 Answers: 1-) C , 2-)D , 3-)A , 4-)A , 5-)A , 6-)E , 7-)B
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