Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

There could 3 intersections rather than 2.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

Yes. this is true. So the unknown variables will be six (the 3 intersection points)

So we need 6 cubics etc etc....

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

Yes, you will need 6 equations when there are 3 points of intersection.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

anonimnystefy,

do you agree with us?

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

How do you construct the polynomials?

MAthematica? I am not familiar with it..

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

There is a better tool for constructing them because it is dynamic. It is called Geogebra.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

Ok, and for solving the system you use Mathematica or the afore mentioned tool?

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

Mathematica will solve the system and geogebra will construct it.

Here is a good one that I will provide all the data for and leave it as a challenge.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

where is the data?

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

Putting it together now. it will take some time to post it. Please hold.

a3 = 1 , point ( 4,18 )

a3 = -0.142857142857141, point ( -4 , 10 )

a3 = 0.017482517482521 point (14 , 40)

a3 = -0.018939393939392 point ( 9 , -10 )

a3 = 0.066137566137551 point ( 10 , 50 )

a3 = -1.111111111111111 point ( 4 , -20 )

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

Ok. Sorry!

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

No problem, I am filling in post #135

A question about the formula in post #99. It has a P(xi) that the formula in post #98 did not have. What is it?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

Its

the respective ofOffline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

I am getting for a3

you are saying that P(x3) is y3 which makes sense.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

Yes I think what you write in #139 is correct.

*Last edited by Herc11 (2013-06-21 06:36:05)*

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

Okay, I will see if I can solve the problem I posted in post 133 - 135.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

I think that it will be solved as you have 6 equations and 6 unknowns..x0---y3

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

Look at these two equations:

do you notice something different?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

No.

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

The a3 has coefficients in it, a0, a1, a2. While the formula for a2 does not have any coefficients in it.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

Yes

So you have only to replace the coefficients with the are equals

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

So, if you now look a_3 you have six unknows. Using 6 cubics I think can leed to a soultion.

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,752

Yes, if you wanted to solve for the a's too. But you can substitute for those a's with earlier terms can you not?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Herc11****Member**- Registered: 2013-06-19
- Posts: 169

What do you mean?

It is the same thing. You have only to solve the set of equations of a3. \

Afterwards, you know the x0-y3. If you wish you can compute a0-a2, but there is no need.

Of course you can substitute. Either you solve for a0 to a2 or for x0-y3 its the same.

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,030

Hi guys

Sorry about not posting all day. has the interpolation worked to reduce the number of needed equations?

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline