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Thread: Calculating and Plotting as a Function of Time

  1. #1
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    Calculating and Plotting as a Function of Time

    hi everyone

    I was having trouble with my math homework and was wondering if someone would be willing to help me. The question is as follows:

    Using the fitted polynomial in part (4)[example: y=0.0003x^4-0.0345x^3+0.8576x^2 - 34.5x + 342.4] and what you have learned in calculus, calculate two polynomials that describe the fetal and placental weight (grams) as a function of time (days), assuming at 16 weeks, a regular fetus is about 100 grams and a regular placenta weighs 120 grams. Plot the fetal and placental weight as a function of time on two new graphs using Desmos Graphing calculator, called Fig 5 and Fig 6. Use proper labels on the x and y axes.

    I have the necessary equations for the question but I am unsure of what to do with them. Can anyone help me out.
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  2. #2
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    Re: Calculating and Plotting as a Function of Time

    Quote Originally Posted by register123 View Post
    hi everyone

    I was having trouble with my math homework and was wondering if someone would be willing to help me. The question is as follows:

    Using the fitted polynomial in part (4)[example: y=0.0003x^4-0.0345x^3+0.8576x^2 - 34.5x + 342.4] and what you have learned in calculus, calculate two polynomials that describe the fetal and placental weight (grams) as a function of time (days), assuming at 16 weeks, a regular fetus is about 100 grams and a regular placenta weighs 120 grams. Plot the fetal and placental weight as a function of time on two new graphs using Desmos Graphing calculator, called Fig 5 and Fig 6. Use proper labels on the x and y axes.

    I have the necessary equations for the question but I am unsure of what to do with them. Can anyone help me out.
    If you have the necessary equations, I recommend plotting the graphs using Desmos Graphing calculator and calling them Fig 5 and Fig 6. Label the x-axis weight (grams) and the y-axis time (days).
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    Re: Calculating and Plotting as a Function of Time

    Quote Originally Posted by SlipEternal View Post
    If you have the necessary equations, I recommend plotting the graphs using Desmos Graphing calculator and calling them Fig 5 and Fig 6. Label the x-axis weight (grams) and the y-axis time (days).
    I have the initial starting equations, I have an example in brackets. I think am supposed to do something with those equations like take the anti-derivative. Like I said, I just don't know where to start with it.
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  4. #4
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    Re: Calculating and Plotting as a Function of Time

    Quote Originally Posted by register123 View Post
    I have the initial starting equations, I have an example in brackets. I think am supposed to do something with those equations like take the anti-derivative. Like I said, I just don't know where to start with it.
    What does the "fitted polynomial" represent? What is the actual fitted polynomial? I accidentally swapped the axes. It should be time on the x-axis and weight on the y-axis. I'm assuming the fitted polynomial is the instantaneous rates of change in weight of fetus and placenta in grams/day as a function of days. Then, take the antiderivative as you suggested. Your antiderivative will have an arbitrary constant C. Then, plug in 16 weeks = 112 days. You want the result for the fetus to be 100 grams. Find the value for C that makes that true. Do the same thing for the equation you have for placenta weight.
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  5. #5
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    Re: Calculating and Plotting as a Function of Time

    Quote Originally Posted by SlipEternal View Post
    What does the "fitted polynomial" represent? What is the actual fitted polynomial? I accidentally swapped the axes. It should be time on the x-axis and weight on the y-axis. I'm assuming the fitted polynomial is the instantaneous rates of change in weight of fetus and placenta in grams/day as a function of days. Then, take the antiderivative as you suggested. Your antiderivative will have an arbitrary constant C. Then, plug in 16 weeks = 112 days. You want the result for the fetus to be 100 grams. Find the value for C that makes that true. Do the same thing for the equation you have for placenta weight.
    Fitted polynomial means making the polynomial degree equal to 4 for the trend line of the graph.So I found the anti derivative of example I gave which was y=0.0003x^4-0.0345x^3+0.8576x^2 - 34.5x + 342.4. Then made y equal to 100 and plugged in 112 for x. When I solved for C, I got a massive negative number. Is that correct? And if it is what is equation that I graph just the anti derivative I got?
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