AP Calc AB Sample Problem Help (Integration)

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Discussion Overview

The discussion revolves around a sample problem from an AP Calculus AB exam related to integration. Participants seek assistance in finding the value of the function f(2) given its derivative and an initial condition.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant describes the problem involving the derivative f'(x) = sin(πe^x/2) and the initial condition f(0) = 1, asking for help in finding f(2).
  • Another participant provides multiple-choice answers for f(2), suggesting that the answer is E (1.157).
  • A suggestion is made to use the Nint feature on the TI-89 calculator for numerical integration to find f(2), indicating the process of integrating sin(πe^x/2) from 0 to 2 and adding f(0).
  • Another approach proposed involves local linear approximation, suggesting that f(x) can be approximated using the derivative at a point, leading to an estimation based on the values provided.

Areas of Agreement / Disagreement

Participants present different methods for solving the problem, but there is no consensus on the best approach or the correctness of the proposed answers. The discussion remains unresolved regarding the exact value of f(2).

Contextual Notes

Limitations include the dependence on the numerical methods suggested and the potential inaccuracies in the approximations used. The discussion does not resolve the mathematical steps necessary to arrive at a definitive answer.

Inspector Gadget
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This is on the sample multiple choice questions in the section in which calculators are permitted. I tried it on my TI-89, and it didn't give an answer...just returned what was input with the integral sign and such...

Given that...

f'(x) = sin(\frac{\pi \times e^x}{2})

... and f(0) = 1, find f(2).

Can someone help?
 
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Forgot...

A.) -1.819
B.) -0.843
C.) -0.819
D.) 0.157
E.) 1.157

Answer: E
 
Try Numerical Integration... Nint feature that is on the TI 89...

Press f3, alpha, b, OR scroll up until you hit the bottom on the list and find Nint.

Should look like...

Nint((sin(pi*e^x/2),x,0,2) then add f(0) to get f(2)... 1.157
 
You could also try local linear approximation:

f(x)\sim f(a)+f^\prime (x)\cdot (x-a)

which in this case would boil down to computing

1+2\sin ({{e^2 \pi}\over {2}} )

since your possible answers are all fairly different (hindsight: the correct answer is very different from the others), this estimation should give you a good enough idea to answer the question.
 

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