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# Finding the order of a polynomial that contains several points. watch

1. So how to do this, form simultaneous equations and elminate?

My teacher said potentially use the Newtons divided diffrence method..
2. (Original post by Mihael_Keehl)
So how to do this, form simultaneous equations and elminate?

My teacher said potentially use the Newtons divided diffrence method..
Mind giving an example? Have you looked up Lagrange interpolation?
3. (Original post by Zacken)
Mind giving an example? Have you looked up Lagrange interpolation?
heard of lagrange multipliers.

So for this:

Suppose you know the following points (x,f(x)):
(-2,85)
(-1,-8)
(1,-20)
(3,40)
(4,307)There is some polynomial,
f(x) = ax4 + bx3 + cx2 + dx + e
You would plug and chug values in to work out a,b,c,d,e right.

I ahve got the answer to that doing simultaneous.

But I would like to know if given say six points, how am I supposed to know what degree the polynomial should be etc.

Thanks..
4. (Original post by Mihael_Keehl)
heard of lagrange multipliers.

So for this:

Suppose you know the following points (x,f(x)):
(-2,85)
(-1,-8)
(1,-20)
(3,40)
(4,307)There is some polynomial,
f(x) = ax4 + bx3 + cx2 + dx + e
You would plug and chug values in to work out a,b,c,d,e right.

I ahve got the answer to that doing simultaneous.

But I would like to know if given say six points, how am I supposed to know what degree the polynomial should be etc.

Thanks..
Look up Lagrange interpolation. If you have n points, then the polynomial is of degree (n-1).
5. (Original post by Zacken)
Look up Lagrange interpolation. If you have n points, then the polynomial is of degree (n-1).
thnx
6. (Original post by Zacken)
Look up Lagrange interpolation. If you have n points, then the polynomial is of degree (n-1).
wow this is interesting and it works, but takes way too long lmao.
7. Oops sorry Mihael I forgot about your pm which I read in the morning. That honestly looks insane tho to me. I cannot see them asking you that in SATII

The tests are so easy compared to Barron's
8. (Original post by Mihael_Keehl)
wow this is interesting and it works, but takes way too long lmao.
Better than n simultaneous equations in n variables...
9. (Original post by Zacken)
Better than n simultaneous equations in n variables...
Agree with you there tbh

Possible Cramer's method could be used too.

Kind of resonates to linear interpolation this q does tbh
10. (Original post by Student403)
Oops sorry Mihael I forgot about your pm which I read in the morning. That honestly looks insane tho to me. I cannot see them asking you that in SATII

The tests are so easy compared to Barron's
Ah thnx, that is reassuring tbh.

Can I just ask is it worth buying the official collegeboard guides for past papers?

Lmao they havent changes sat 2 syallbus for at least 8 years lmfao
11. (Original post by Mihael_Keehl)
Ah thnx, that is reassuring tbh.

Can I just ask is it worth buying the official collegeboard guides for past papers?

Lmao they havent changes sat 2 syallbus for at least 8 years lmfao
Yeah they're really getting complacent :P

Nah I would stick to Barron's because if you do Collegeboard it will seem like piss and you might start to lose momentum. What are you getting atm if you don't mind? And are you doing the May one?
12. (Original post by Student403)
Yeah they're really getting complacent :P

Nah I would stick to Barron's because if you do Collegeboard it will seem like piss and you might start to lose momentum. What are you getting atm if you don't mind? And are you doing the May one?
Hahahaha.

Good advice, this boy in my class did phy too and got 800. He said he barely revised lmao.

tbh not really focusing a lot on sat2s, usually just do the topic area as I am covering the a level one. But 680 on phy so far. Maths is 800 but gets wrecked when I do chungs papers. They are profoundly difficult lmao.

Yeah will probably do then the a levels start!

You're finished with the whole rigmarole right?
13. (Original post by Mihael_Keehl)
Hahahaha.

Good advice, this boy in my class did phy too and got 800. He said he barely revised lmao.

tbh not really focusing a lot on sat2s, usually just do the topic area as I am covering the a level one. But 680 on phy so far. Maths is 800 but gets wrecked when I do chungs papers. They are profoundly difficult lmao.

Yeah will probably do then the a levels start!

You're finished with the whole rigmarole right?
Yeah that's definitely possible! Although it's annoying how we have to learn the A2 components early :/

Dw about the non collegeboard ones - some are much, much more difficult. As I always used to say to my friends, if you can hit 750 in Barrons once in a practice, I guarantee you'll get 800 on the day. Physics is getting there

Ahh I did that last year ^^ Don't worry if anyone asks you "but how will you revise for A levels?". May sitting last year was much closer to AS levels but I didn't feel any pressure for revision of AL due to revising for SAT. You'll be fine!

Yes
14. (Original post by Student403)
Yeah that's definitely possible! Although it's annoying how we have to learn the A2 components early :/

Dw about the non collegeboard ones - some are much, much more difficult. As I always used to say to my friends, if you can hit 750 in Barrons oncein a practice, I guarantee you'll get 800 on the day. Physics is getting there

Ahh I did that last year ^^ Don't worry if anyone asks you "but how will you revise for A levels?". May sitting last year was much closer to AS levels but I didn't feel any pressure for revision of AL due to revising for SAT. You'll be fine!

Yes
Thanks for the advice, this is very true tbh I agree.
15. (Original post by Mihael_Keehl)
Thanks for the advice, this is very true tbh I agree.
All the best sorry I couldn't help this time
16. (Original post by Student403)
All the best sorry I couldn't help this time
dw Zacken had the name of the method I was looking for, so long lmao but just a small step from linear interpolation from fp1 thnx tho
17. (Original post by Mihael_Keehl)
dw Zacken had the name of the method I was looking for, so long lmao but just a small step from linear interpolation from fp1 thnx tho
Great

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