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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: 87,258

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.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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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: 87,258

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.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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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: 87,258

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.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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