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#1 2010-06-18 10:58:14

lakeheadca
Member
Registered: 2010-01-31
Posts: 37

distance problem

What is the difference b/w point A and B.
if the Equation is

-X^4+5x^3+4X^2+6X+8

Anyone know how to solve this problem, since I don't remember exact equation but the the answer was like 6 in, 4 in or 8 in.
There is no more information in the question, just one fig

View Image: distance.GIF

Last edited by lakeheadca (2010-06-18 11:28:49)

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#2 2010-06-18 11:15:43

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,472

Re: distance problem

Hi;

What is point A and point B? What is b/w?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#3 2010-06-18 11:29:37

lakeheadca
Member
Registered: 2010-01-31
Posts: 37

Re: distance problem

There is no more information in the question, just one fig

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#4 2010-06-18 11:40:41

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,472

Re: distance problem

Hi;

I can solve it but first I have to ask. What is this problem for? Is this a book problem, contest problem, made up problem? Your answer is going influence my method!

I can solve the distance between point A and B if that is what you want?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#5 2010-06-18 12:38:47

lakeheadca
Member
Registered: 2010-01-31
Posts: 37

Re: distance problem

this question was in my math licensing exam.

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#6 2010-06-18 13:00:59

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,472

Re: distance problem

Hi;

In my opinion the question is awful. I have to make so many assumptions. Now, what the heck is that drawing? Are we supposed to assume that is the xy axis without it being labelled? Am I supposed to assume that graph at the ends is touching the x axis, making A amd B roots.

Did they expect you to be able to get the roots to that quartic? Not an easy job without a computer. Do they want the straight line distance between A and B or the Arc length distance?

Now assuming that is the xy axis and  A and B are touching it and that squiggly mess is the graph of the function, which it is not. I solve like this:

-X^4+5x^3+4X^2+6X+8 = 0 has 2 real roots thay are:

x = -1 and x = 5.89102041

So the straight line distance is 6.89102041 which is none of your choices.

The arc length distance between A and B is 327.039 also not one of your choices.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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