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Math Help - Help with left hand Riemann sum?

  1. #1
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    Help with left hand Riemann sum?

    I have this Riemann sum question: Help with left hand Riemann sum?-capture9.jpgand I thought I knew how to do the left hand riemann sum but now I'm unsure. Basically I've used it before but when I try to with these points I'm just getting really confused because they're all under the x-axis. I had to kind of do it upside down. My answer was -13.5 but I wasn't sure if I should make it 13.5 because it's the area? Also, can you check to see if I did the math right for it? 13.5 negative or positive could be wrong :/ Thanks!
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  2. #2
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    Re: Help with left hand Riemann sum?

    It is asking you to calculate the Riemann sum. It is not asking you to calculate the area. The Riemann sum calculates the area under the curve. Area above the curve could be considered "negative" area. In other words, -13.5 is correct.
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    Re: Help with left hand Riemann sum?

    Quote Originally Posted by SlipEternal View Post
    It is asking you to calculate the Riemann sum. It is not asking you to calculate the area. The Riemann sum calculates the area under the curve. Area above the curve could be considered "negative" area. In other words, -13.5 is correct.
    Okay, thanks!
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    Re: Help with left hand Riemann sum?

    Quote Originally Posted by canyouhelp View Post
    Okay, thanks!
    I took your word for it. I just did the calculation, and the left-hand Riemann sum with four subintervals would be -11, not -13.5. Did you use 8 subintervals?
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    Re: Help with left hand Riemann sum?

    Quote Originally Posted by SlipEternal View Post
    I took your word for it. I just did the calculation, and the left-hand Riemann sum with four subintervals would be -11, not -13.5. Did you use 8 subintervals?
    Oh wow, thanks for catching that! Yes, I messed up and used 8 sections. I need to be more careful about following the question.
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