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Kiiten superhelp thread

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Reply 80
Avatar for Zacken
Zacken
22
Original post by kiiten
if you have to determine if a point is maximum of minimum do you use the first or second derivative? Also, how do you know if it is max or min - is it +ve is max?


When the first derivative is zero at a point, that point is a stationary point.

When the second derivative is +ve at that point, the stationary point is a minimum.

When the second derivative is -ve at that point, the stationary point is a maximum.
Reply 81
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kiiten
OP
18
Original post by Zacken
When the first derivative is zero at a point, that point is a stationary point.

When the second derivative is +ve at that point, the stationary point is a minimum.

When the second derivative is -ve at that point, the stationary point is a maximum.


Thank you!! - Does that apply for any other point on a curve?
Reply 82
Avatar for Zacken
Zacken
22
Original post by kiiten
Thank you!! - Does that apply for any other point on a curve?


What d'you mean by that? It applies to any stationary point on a curve. A maximum or minimum has to be a stationary point.
Reply 83
Avatar for kiiten
kiiten
OP
18
Original post by Zacken
What d'you mean by that? It applies to any stationary point on a curve. A maximum or minimum has to be a stationary point.


Oops sorry I forgot that a max/min point has to be stationary. Ignore the question :smile:
Reply 84
Avatar for kiiten
kiiten
OP
18
2 separate cast circle question. Please could someone show me where i went wrong?
1458593534493579759615.jpg
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1458593601510-2057875549.jpg500.4KB
Reply 85
Avatar for Notnek
Notnek
21
Original post by kiiten
2 separate cast circle question. Please could someone show me where i went wrong?
1458593534493579759615.jpg
Attachment not found

1st one : Try expanding (3p+q)(p−2q)(3p+q)(p-2q). It's nearly correct.

2nd one : It looks like you haven't performed any sin⁡−1\sin^{-1}. You have used 0.5\sqrt{0.5} as your angle instead of sin⁡−10.5\sin^{-1}\sqrt{0.5}.
Reply 86
Avatar for kiiten
kiiten
OP
18
Original post by notnek
1st one : Try expanding (3p+q)(p−2q)(3p+q)(p-2q). It's nearly correct.

2nd one : It looks like you haven't performed any sin⁡−1\sin^{-1}. You have used 0.5\sqrt{0.5} as your angle instead of sin⁡−10.5\sin^{-1}\sqrt{0.5}.


Thanks i got the 2nd one right now - ill try the 1st one later (did i get the +ve and -ve the wrong way round in the bracket?)

Posted from TSR Mobile
Reply 87
Avatar for Notnek
Notnek
21
Original post by kiiten
Thanks i got the 2nd one right now - ill try the 1st one later (did i get the +ve and -ve the wrong way round in the bracket?)

Posted from TSR Mobile

Yes that was the mistake.
Reply 88
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kiiten
OP
18
How would the diagram look for this question?

Screenshot 2016-03-29 15.28.09.png
Reply 89
Avatar for kiiten
kiiten
OP
18
I think this thread has died :'(
Original post by kiiten
How would the diagram look for this question?

Screenshot 2016-03-29 15.28.09.png


@Zacken
Reply 91
Avatar for Zacken
Zacken
22
Original post by thefatone


The user has posted this in another thread.
Original post by Zacken
The user has posted this in another thread.


oh i see

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