Mathrookie94

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These are questions asked by Mathrookie94

Hello :) 

I have a math problem, where I first need to use Linear regression to find the equation based on a set of data. I did that, no problem. 

However, in the next part of the problem I need to check if the residuals are under "normal distribution". Usually, I check if a dataset is normally distributed via "QQ-plot", and there will be no problems. But this time, because I need to check the residuals, I need to use the "residualQQplot(data,LinReg)" command to make it happen. But when I read the mean-value, mu, it says "-0," and nothing else? I know it should be "-3,2752*10^-15. 

The standard deviation is correct.

How do I fix this, so the residualQQplot shows me the right result? 

I have attached the worksheet here. worksheet_-_linear_reg_and_residuals_for_normal_distribution.mw

Thank you! 

Hello :) 

I don't know how to further simplify a complex equation as a solution to a differential equation. I have already tried "simplify(%)" etc. but it only repeats the same equation. I also know that it can be simplified to a much more "nice" equation in WordMat and TI-Nspire. I have attached a screenshot of my work. 

Thank you! 

with(Gym)

with(plots)

with(DEtools)

 

I need to find the solution to the differential equation: y'=0.0768*f(x)^2/3-0.0102*f(x) when f(1)=59. 

 

dsolve({diff(f(x), x) = 0.768e-1*f(x)^(2/3)-0.102e-1*f(x), f(1) = 59}, f(x))

f(x) = 2097152/4913+(384/4913)*(16384-4352*59^(1/3)+289*59^(2/3))*exp(17/2500-(17/2500)*x)+(1/4913)*(835584*59^(1/3)-110976*59^(2/3)-1807285)*exp(51/5000-(51/5000)*x)+(49152/4913)*(17*59^(1/3)-128)*exp(17/5000-(17/5000)*x)

(1)

simplify(%)

f(x) = 2097152/4913+(384/4913)*(16384-4352*59^(1/3)+289*59^(2/3))*exp(17/2500-(17/2500)*x)+(1/4913)*(835584*59^(1/3)-110976*59^(2/3)-1807285)*exp(51/5000-(51/5000)*x)+(49152/4913)*(17*59^(1/3)-128)*exp(17/5000-(17/5000)*x)

(2)

 

Download worksheet_.mw

Hello, 

I have come across a problem in Maple, when I try plotting af slope field from my differential equation. 

I have tried different ways of defining the ODE, but when I use it in the command of "linjeelementer" (Danish for line elements - It's a command that's part of a package called "With (Gym)" in Maple, it gives me the error: Error, (in DEtools/DEplot/CheckDE) - Derivatives must be given explicitly. 

I don't understand what derivatives I must "give explicitly"?

Translation of the relevant sentences if anyone needs it when looking at the screenshot:

"I need to draw a slope field for the differential equation along with the solution curve for the population growth in India after 1960.

I define the differential equation:
ODE := -0.000032229*y^2 + 0.065843*y - 15.103"

"I am drawing the slope field for the differential equation along with the solution curve for the population growth in India after 1960, i.e., the solution curve that passes through the point (0,449):I am drawing a slope field for the differential equation along with the solution curve for the population growth in India after 1960, i.e., the solution curve that passes through the point (0,449):
linjeelementer(ODE, y(t), t = 0 .. 350, y = 0 .. 2000)"

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