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Math Help - Trapezoidal rule problem

  1. #1
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    Trapezoidal rule problem

    integral (limits: a = -1 and b = 1) or 5e^-2x^2 (the Latex max confuse: 5e^-2x^2) using 4 strips.

    Length = 2 and width = 0.6

    E = 0.677 + 0.677 = 1.354

    M = 0.169 + 0.169 = 0.338

    f(x) dx = 1/2 w (E + 2M)

    = 0.25 (1.354 + 2 * 0.338)

    = 0.5075

    But the answer is actually 5.87...
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  2. #2
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    Quote Originally Posted by zapparage View Post
    integral (limits: a = -1 and b = 1) or 5e^-2x^2 (the Latex max confuse: 5e^-2x^2) using 4 strips.

    Length = 2 and width = 0.6

    E = 0.677 + 0.677 = 1.354

    M = 0.169 + 0.169 = 0.338

    f(x) dx = 1/2 w (E + 2M)

    = 0.25 (1.354 + 2 * 0.338)

    = 0.5075

    But the answer is actually 5.87...
    You have the width wrong. Two divided by four gives w = 0.5.
    f(x)=5e^{-2x^2}
    Integral = 0.5*w*(f(-1) +2*(f(-.5)+f(0)+f(0.5))+f(1))
    Integral = 0.5*0.5*(0.677+2*(3.03+5+3.03)+0.677)
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  3. #3
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    Sorry it was a typo. I did actually use 0.5
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