Calculus Notes 5.1: Approximating and Computing Area. How would you find the area of the field with that road as a boundary?

Transcription

1 Calculus Notes 5.1: Approximating and Computing Area. How would you find the area of the field with that road as a boundary? Say a road runner runs for 2 seconds at 5 m/s, then another second at 15 m/s, 3 more seconds at 10 m/s, and last 2 more seconds at 5 m/s. How far does it travel total?

2 Calculus Notes 5.1: Approximating and Computing Area. )

3 Calculus Notes 5.1: Approximating and Computing Area. 2 R f ( ) = [ ] Example 1: Calculate R 4 and for x x on the interval 1,3. 6 Then calculate,, and M. R 5 5 L 5 Ĝ Which one is an overestimate? Underestimate?

4 Calculus Notes 5.1: Approximating and Computing Area. x = b a N

5 Calculus Notes 5.1: Approximating and Computing Area. L8 8 1 f ( ) [ ] Example 2: Calculate R 8,, and M for x =x on the interval 2,4. ;

6 Calculus Notes 5.1: Approximating and Computing Area. {

7 Calculus Notes 5.1: Approximating and Computing Area. { x = b a N

8 Calculus Notes 5.1: Approximating and Computing Area. {

9 Calculus Notes 5.1: Approximating and Computing Area. Example 1: Use linearity and formulas [3] [5] to rewrite and evaluate the sums. a n b. j( j 1) j= 0 n= 51 {

10 Calculus Notes 5.1: Approximating and Computing Area. Example 2: Calculate the limit for the given function and interval. Verify your answer by using geometry. a. limr f x 9x 0,2 N N ( ) = [ ] b. limln f( x) = x + 2 [ 0,4] N 1 2 )

11 Calculus Notes 5.1: Approximating and Computing Area. R N Example 3: Find a formula for and compute the area under the graph as a limit. 1 a. f x x 2 0,4 2 ( ) = + [ ] ( ) 2 = [ ] b. f x x 1,5 s

12 Calculus Notes 5.2: The Definite Integral From 5.1: When you add up the rectangles, do they all have to be the same width? s For Riemann sum approximations, we relax the requirements that the rectangles have to have equal width.

13 Calculus Notes 5.2: The Definite Integral s

14 Calculus Notes 5.2: The Definite Integral R f P C f( x) = 7 + 2cos 3 ( ) Example 1: Calculate,,, where on P : x0 = 0< x1 = 1< x2 = 1.7< x3 = 3.1< x4 = 4 C : { 0.3,1.1,2.5,3.4 } What is the norm P? s x x [ 0,4]

15 Calculus Notes 5.2: The Definite Integral *

16 Calculus Notes 5.2: The Definite Integral

17 Calculus Notes 5.2: The Definite Integral *

18 Calculus Notes 5.2: The Definite Integral Example 2: Calculate 0 5 ( ) 3 x dx and 5 3 xdx 0 *

19 Calculus Notes 5.2: The Definite Integral *

20 Calculus Notes 5.2: The Definite Integral Example 3: Calculate 4 7 ( 2 + ) x x dx *

21 Calculus Notes 5.3: The Fundamental Theorem of Calculus, Part I Recall from 5.2 Reading Example 5: xdx + xdx = xdx Note that 1 F x x 3 3 ( ) = xdx = ( 3 3 ) xdx = xdx xdx = 7 4 = ( 279 ) = is an antiderivative of 2 x So we can re-write it as: xdx F ( 7) F( 4) =

22 Calculus Notes 5.2: The Definite Integral Example 1: evaluate the integral using FTC I: 0 9 a. 2dx 1 1 ( ) b. 5u u u du 姠 3π 4 c. sin θ d θ π 4

23 Calculus Notes 5.2: The Definite Integral Example 2: Show that the area of the shaded parabolic arch in figure 8 is equal to four-thirds the area of the triangle shown. A 2 4 A+B 2 ( )( ) y = x a b x B 姠

24 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II From 5.3 From 5.4 姠

25 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II Proof of FTC II: First, use the additive property of the definite integral to write the change in A(x) over [x,x+h]. x+ h x x h A ( x + h) A( x)= ( t) dt f ( t) f dt = f ( t) + a a x In other words, A(x+h)-A(x) is equal to the area of the thin section between the 姠 graph and the x-axis from x to x+h. dt

26 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II Proof of FTC II continued: To simplify the rest of the proof, we assume that f(x) is increasing. Then, if h>0, this thin section lies between the two rectangles of heights f(x) and f(x+h). We have limf h 0+ ( x + h) = f ( x) So the Squeeze Theorem gives us: So we have: hf ( x) Area of small rectangle 姠 A( x + h) A( x) hf ( x + h) Area of section Area of big rectangle Now divide by h to squeeze the difference quotient between f(x) and f(x+h) ( x + h) A( x) A f ( x) f + h because f(x) is continuous, and limf h 0 ( x h) ( x) = f ( x) A similar argument shows that for h<0:

27 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II Proof of FTC II continued: Equation 1 Equation 2 A ( x) A ( x) = f ( x) Equation 1 and Equation 2 show that exists and. Y

28 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II 쥠

29 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II F ( 1) F ( 0) π F 4 Example 1: Find,, and, where F ( x) = x tantdt 1 E

30 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II Example 2: Find formulas for the functions represented by the integrals. a. x 2 ( t t) dt b. 0 x e t dt 쥠 c. x dt 2 t

31 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II Example 3: Calculate the derivative. a. d dθ 0 ( cot u) 1 du b. 2 d x t dx t dt 䢐

32 Calculus Notes 5.4: The Fundamental Theorem of Calculus, Part II Example 4: Explain why the following statements are true. Assume f(x) is differentiable. (a) If c is an inflection point of A(x), then f ( c) = 0 (b) A(x) is concave up if f(x) is increasing. 쥠 (c) A(x) is concave down if f(x) is decreasing.

33 6 0 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. v ( t) dt = 6 ( 2 t 3t) 6 2t 3dt 0 = = 1 ( ) 2 2 ( 6) 36 ( ) ( 0) 30 ( ) = = 18m 6 0 쥠 ( t) dt = Position function: s( t) Velocity function: s ( t) = v( t) Acceleration function: s t = v t = at ( ) ( ) ( ) Example 1: Find the total displacement and total distance traveled in the interval [0,6] by a particle moving in a straight line with velocity ( t ) 6 0 v 2t 3dt= 0 = 2t 3m/s t = v v ( t) ( t) 3 < 0fort < 2 3 > 0fort > 2 v =2t 3m/ s 3 2 = tdt + 2t 3dt t 3dt 1.5 2t 3dt ( 3 ) ( 3 ) 5. t t t = t 0 ( 18 ( 225. )) ( ( 225) 0) =. = 22.5

34 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. Example 2: The number of cars per hour passing an observation point along a highway is called the traffic flow rate q(t) (in cars per hour). t ( ) a. Which quantity is represented by the integral qt t ( ) b. The flow rate is recorded at 15-minute intervals between 7:00 and 9:00 AM. Estimate the number of cars using the highway during this 2-hour period. 䢐 2 2 qtdt t1 the observation point during the time interval [ t, ] t 1 dt The integral represents the total number of cars that passed 1 t 2

35 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. Find the integral of the following: a. ( 2 x x + ) dx b. 2xcos( x ) c. 1+ 2xdx ۵

36 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. Find the integral of the following: d. x dx ( ) 2 e. 2 x + 9 cosx dx f. 1+ 2x 2 dx ۵

37 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. du = du dx dx so ۶ so This equation is called the Change of Variables Formula.

38 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. Example 3a: x x + 6x + dx 1 كا ۵

39 Calculus Notes 5.5 & 5.6: Net or Total Change as the Integral of a Rate and Substitution Method. Example 3b: 2 x x + 6x + dx 1 쥠

40 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Calculate 1 x dt t bdt = lnx So = lnt = lnb lna= ln b b a a t a x e dx= e x ۶ كا

41 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay 12 dt Example 1: Evaluate the definite integral 2 3t+ 4 쿐

42 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay 1 5 dx Example 2: Evaluate the definite integral x ٧

43 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Example 3: Evaluate the indefinite integral xdx 4 x + 1 퀠

44 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Example 4: Evaluate the definite integral x dx ٧

45 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay 큰

46 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay

47 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Example 5: In the laboratory, the number of Escherichia coli bacteria grows exponentially with growth constant k= 0.41( hours). 1 Assume that 1000 bacteria are present at time t=0. a. Find the formula for the number of bacteria P(t) at time t. b. How large is the population after 5 hours? 타 c. When will the population reach 10,000?

48 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay y = 3y Example 6: Find all solutions of. Which solution satisfies? ( ) y 0 = 9 ઠ٧ Example 7: The isotope radon-222 decays exponentially with a half-life of days. How long will it take for 80% of the isotope to decay?

49 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Example 8: Pharmacologists have shown that penicillin leaves a person s bloodstream at a rate proportional to the amount present. a. Express this statement as a differential equation. b. Find the decay constant if 50 mg of penicillin remains in the bloodstream 7 hours after an initial injection of 450 mg. 뿐 ۶ c. Under the hypothesis (b), at what time was 200 mg of penicillin present?

50 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Example 9: A computer virus nicknamed the Sapphire Worm spread throughout the internet on January 25, Studies suggest that during the first few minutes, the population of infected computer hosts increased exponentially with growth constant k= a. What was the doubling time for this virus? b. If the virus began in 4 computers, how many hosts were infected after 2 minutes? 3 minutes? 1 s Example 10: In 1940, a remarkable gallery of prehistoric animal paintings was discovered in the Lascaux cave in Dordogne, France. A charcoal sample from the cave walls had a C to C ratio equal to 15% of that found in the atmosphere. Approximately how old are the paintings? ٩ كا

51 Calculus Notes 5.7 & 5.8: Further Transcendental Functions & Exponential Growth and Decay Example 11: Is it better to receive $2000 today or $2200 in 2 years? Consider r=0.03 and r=0.07. Example 12: Chief Operating Officer Ryan Martinez must decide whether to upgrade his company s computer system. The upgrade 준٩ costs $400,000 and will save $150,000 a year for each of the next 3 years. Is this a good investment if r=7%?