What was the appearance of your Normal Equations? I'll suggest one. Youtell me the other.
, of course.
I have an assignment to do in maths and I've encountered some problems. The teacher I have is not very helpful so I hope that I'll receive some help from here instead. Basically, we have to design a function to fit these variables:
x 1.7 2.0 2.9 4.1 5.6 6.3 7.0 8.0 10.0 13.9
y 42.0 21.0 10.3 6.8 5.1 4.8 4.4 4.1 3.7 3.2
First I thought of using a simultaneous equation to solve for a and c by using this formula: y = a(1/x)+c... but it ended up weird and I'm not sure of what x and y variables to use... I'm not even sure of the formula I came up with. So, well, what to do? I know that many possible ways can be used to create an appropriate graph to fit the variables and one of them is supposed to be by simultaneous equations which I personally prefer as I cannot handle complex maths. Guided help would be kind as I am to describe the process and such.
Thank you! (:
"y = a(1/x)+c... "
Without some background in the calculus, this is a very difficult task. You may be left with simply guessing. Pick values for 'a' and 'c' tha tmake sense and adjust them to see what happens. You should be able to do this in MS Excel with reasonable accuracy.
Sorry if I sound rude, but I am more or less desperate right now as this is only the basic function that is needed to do all the rest.
1. Plot the points (use technology) to get an idea of the sort of regression model you might want to try.
2. Use technology to do the appropriate regression.
eg. Power regression. I get where and and .
Why on Earth would you try doing this by hand ....?
Who said anything about "random"? Use some sense? How many exponential equations have you seen in your lifetime? Maybe logarithmic sould be better. No one is really recommneding guessing. Use ALL the tools availalbe to you. THE MOST VALUABLE tool is your own experience.I really do not know what I am doing and putting "random" values into the formula is not that wise, but I've tried and the results are not very pretty and thus I hope that someone can help me and show me how it can be done simultaneously...
I didn't detect any rudeness.Sorry if I sound rude, but I am more or less desperate right now as this is only the basic function that is needed to do all the rest.
I would suggest one thing. Try Rational function approximation is a joy.
2. We do not get to use technology before we've done a fitting graph first. The instructions say "What type of function models the behaviour of the graph? Explain why you chose this function. Create an equation (a model) that fits the graph." and then "Use technology to find another function that models the data. On a new set of axes, draw your model function and the function you found using technology. Comment on any differences."
And the results you got, are they not derived by technology? The graph seems to fit and if you haven't used technology could you then please show me how you got those results using calculations?
Are you not supposed to be able to solve it by using simultaneous equations or any other method without using technology, or am I just supposed to guess until I get an appropriate graph?
Seriously, I'm having a very hard time finding the parameters of the function y= a(1/(x-b))+c.... can someone please, please help me... I've done some very random guessing of what these parameters may be and got f(x) = 10 / (x - 1.5) + 2.5, but still, I really have to show how I found those parameters by using calculations and I still do not believe that it is the appropriate graph I've got and... ah.... help is very appreciated, I have no, no clue at all.
My teacher's expectations are high, but my work will be assessed by someone else outside our school and I have the right to get help with my work and discuss with other people about how to solve the task. My own knowledge about the subject, however, is very limited due to the fact of intense studying of my other subjects, which I now regret (if that is not obvious enough) and thus I really hope that I will get some further help over here...
Telling us methods you do NOT know really is not very helpful.
Projects like this may take a bit of thoughtful guessing.
Look what happens as the graph moves down the positive x-axis. Does it seem to be going somewhere? Does it level off? The answer to these questions will help you to judge a good value for "c"
Look what happens as the graph moves up the positive y-axis. Does it seem to be going somewhere? Does it level off? The answer to these questions will help you to judge a good value for "b"
Keep in mind that either or both could be zero (0).
If,m in this way, you manage rational guesses for towo parameters, it shoul dnot be too difficult to find some reasonable sord of approximation for the last parameter.
You build models by intuition.
You solve difficult problems often by simplification.