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# c4 parametric help watch

1. Find and classify, the stationary points on the curves with parametric equations using first differential method. x=t^2 and y=t^3 -3t
dy/dx= 3t^2-3/2t

The stationary points are (1,2) when t =-1 and when t=1 the stationary point is (1,-2). The problem I'm having is when using first differential method I get that the points are inflection points, however this is wrong and they should be maximum and minimum points. Any help would be appreciated.
Thanks
2. It may be useful to show your workings.
3. (Original post by gooner1010)
Find and classify, the stationary points on the curves with parametric equations using first differential method. x=t^2 and y=t^3 -3t
dy/dx= 3t^2-3/2t

The stationary points are (1,2) when t =-1 and when t=1 the stationary point is (1,-2). The problem I'm having is when using first differential method I get that the points are inflection points, however this is wrong and they should be maximum and minimum points. Any help would be appreciated.
Thanks
Don't you mean second?
4. (Original post by gooner1010)
Find and classify, the stationary points on the curves with parametric equations using first differential method. x=t^2 and y=t^3 -3t
dy/dx= 3t^2-3/2t

The stationary points are (1,2) when t =-1 and when t=1 the stationary point is (1,-2). The problem I'm having is when using first differential method I get that the points are inflection points, however this is wrong and they should be maximum and minimum points. Any help would be appreciated.
Thanks
How did you test your stationary points?
5. (Original post by h3rmit)
Don't you mean second?
I tried second and I got the correct answer however the questions says use the first differential
6. (Original post by gooner1010)
I tried second and I got the correct answer however the questions says use the first differential
Also for the spec im doing, they only expect you to know first differential
7. (Original post by gooner1010)
I tried second and I got the correct answer however the questions says use the first differential
That works too, with t=.9 and t=1.1, then the negatives
8. (Original post by h3rmit)
That works too, with t=.9 and t=1.1, then the negatives
is there a specific range when using first differential method? I tried 0.5 and 1.5
9. (Original post by gooner1010)
is there a specific range when using first differential method? I tried 0.5 and 1.5
As close to the point you're using as possible is generally good idea, usually 0.1 or less away
10. (Original post by h3rmit)
That works too, with t=.9 and t=1.1, then the negatives
When I put 0.9 I get a negative value and 1.1 get a positive value, wouldn't that be a point of inflection?
11. (Original post by gooner1010)
When I put 0.9 I get a negative value and 1.1 get a positive value, wouldn't that be a point of inflection?
No, positve on both sides or negative on both sides would be a point of inflection. Positive on one side and negative on the other means it's a turning point, like the hump of a cubic
12. (Original post by h3rmit)
No, positve on both sides or negative on both sides would be a point of inflection. Positive on one side and negative on the other means it's a turning point, like the hump of a cubic
ahhh, I've got it now. Thankyou for the help

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