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Homework Help: Definite Integral Calculator Problem

  1. Mar 28, 2012 #1

    1. The problem statement, all variables and given/known data

    I'm solving the definite integral 4π∫{0,3/2}(x^3)dx

    For some reason I get a different answer solving by hand and using my TI-89 than I do when I use an online calculator or my TI-36X Pro. I have to use the TI-36X Pro to take my Engineering FE exam in 2 & 1/2 weeks and need to know why I'm getting these different answers.

    Does anyone see what I'm missing?

    3. The attempt at a solution

    Solving by hand I get πx^4|{0,3/2} = π(3/2)^4 - 0 = 81π/16

    This is also what the solution shows, and what my TI-89 calculator gives me as an answer.
    But for some reason when I type that same integral into my TI-36X Pro calculator, or an online integral calculator like: <http://www.solvemymath.com/online_math_calculator/calculus/definite_integral/index.php> [Broken]
    I get the answer 15.904 which is 5π/16.

    Thank you very much!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Mar 28, 2012 #2


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    Science Advisor
    Homework Helper

    The first answer is correct. 81π/16=15.90431. 5π/16=0.98174. I don't think there is anything wrong the calculators.
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