Is Curve x=3t^2, y=e^2t+1 Concave Up/Down at (3,e^3)?

[rcmango]

Homework Statement

Determine whether the curve x = 3t^2, y = e^2t+1 is concave up or concave down at the point (3, e^3)

thanks for any help with this one.

Homework Equations

The Attempt at a Solution

know i need to take the double derivative. Also that would be 6
and 4e^2t+1

what point do i put back into the double derivative. Also, do I use 3 and e^3? they represent x, y, so do they plug into the equation appropriately, or back into t? please help.

 

[quasar987]

If you know how to determine concavity or concavity when given a function y(x), then I suggest you try to "eliminate" that nasty t and try to write y as a function of x!