Tuesday, March 5, 2013

Scribe Post 5-8 March

Knowing that the class was to begin with a thrilling Supercorrection Follow-up Test, all students merrily frolicked into room 219 as Crockett played "Concerning Hobbits." This joyful tune made many a happy face on this fateful day of integration. Proceeding with gusto, the class delved into the test from 33 minutes past the hour of nine until time ran out 13 minutes after ten o'clock. The scribe post of the exceptionally affluent and widely respected Sir William Billiam Shilliam Dilliam Strongclaw Proudfoot Covenhoven III (seen below) was then thoroughly analyzed and appreciated before moving on to the topic at hand: Integration by Substitution.

His Eminence Sir William

Task 1: Solve the following



a. long division



b. substitution



BREAK
Apparently there was not supposed to be a scribe post for Tuesday or Wednesday, so we will continue on Thursday.

If you are having trouble with Integration by Substitution when you change the limits of the integral from terms of x to terms of u, check out this video. It particularly helps with IW#1, problems 54, 55, 59, and 71.

THURSDAY:

Today we began by reminding the whole class to sign up for their AP Calculus Exam. If you forget how to, you can go to the guidance office to figure that ish out.

Supercorrection follow-up tests came back in after that. Our class continues to improve on these tests each time! We proceeded to go over the answers to each question

1. Physics bums need to remember the superiority of radians.
2. Trapezoid Rule (remember area of a trapezoid)
                  
The two bases are actually two heights in this problem set, and the height is correspondent to the width of each trapezoid.

3. Remember to divide the integral by the interval to get the average value.

4. a. nDeriv(v(t))
4. b. total distance: 
The absolute value sign accounts for areas between the curve and x axis that are negative (when the curve dips below the x axis).
4. c. Fundamental Theorem of Calculus: 
           In the problem set: a = 0, b = 5, x(0) = 4
           So,

            

5. Check your answer by deriving! If it didn't work, then try to figure out what was missing.

6. Any integral of an exponential function with base e will always include e raised to the original power in the answer. This can provide a good starting point for these problems. By taking the derivative of the integrand, you can identify which constants are necessary to transform the function into the integral.

7. Graph it!

8. Split apart the integral by Addition Rule and integrate!

9. a. Zero Rule of Integration
9. b. Order of Integration
9. c. Odd functions are symmetrical about the origin
9. d. Addition/Subtraction of Integrals

END OF SUPERCORRECTION REVIEW

THE FINAL PROBLEM!

Area bounded by two curves?
Not all math is nice, some is sketchy.
Area_G1


2000 AP Calculus Question 1

a. As a Sum of Rectangles, and, by extension, and integral
     choose a base (a change in x)
     then find your heights (height of upper function-height of lower function <= always positive)
          ^difference between two functions
      set up your integral (upper function - lower function <= this changes depending on interval)
            
        = point of intersection, so the point where  (Solver, then integrate)

Small Break:

   Golden Way: Finding area between any two curves
      
          ^ensures that the height will always be positive
   If there are three curves => you need multiple integrals

b. The volume of the solid when revolved around the x axis? What?!
      1. Take representative rectangle (selection from area btw curves)
      2. Revolve around axis to create washer/ CD shape.
      3. find the area and then the volume.
  Area of two concentric circles = area of larger - area of smaller
  So, since the base e function is larger than the cosine function, and area of a circle = πr^2
           
This is advanced stuff though, we will cover it in more detail later. Feel no obligation to understand this at this juncture. We will ease into it.

IW#3 p. 399/ 2, 4, 10, 14

2. area btw
      




4. area between two vertical (think horizontal rectangles)


            = 4/3 or 1.33333....

10. 
     Watch out, you can solve for x or y on this one!
          
          The second integral in the second one is just a right triangle, so use Pythagorus!
          Answer: 0.83333333....

This area work can be tricky, but is is the exact same process as finding the combined area of two curves. The only difference is that we are using subtraction instead of addition. If you are still confused, then ask Patrick JMT. Visual Calculus does a great job showing step-by-step solutions to a number of "area between two curves" problems.

14. space between
       
First: Determine dx or dy formula (think about the rectangles => vertical vs. horizontal)
          
Without tech: find intersections and integrate with smaller function subtracted from the larger.
        Intersections: (-1, 3) and (2,0)



p. 401/ 49


Find the intersections:

x = 0.8241323....

Set up the integral:



Next scribe will be Gabe (Eddie dropped out).

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