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

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

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

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

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.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

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

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

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

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 to 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.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

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

this question was in my math licensing exam.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

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.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

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