Thread: parametric curves

x=t^2
y=t^3-3t

a) Show that C has two tangents at the point (3,0) and find their equation.
b) Find the point on C where the tangent is horizontal or vertical.
c) Determine where the curve is concave upward or downward?

I was able to do part a and b, but I'm stuck on part c. How do you find the second derivative of this curve?

Originally Posted by cityismine

x=t^2
y=t^3-3t

a) Show that C has two tangents at the point (3,0) and find their equation.
b) Find the point on C where the tangent is horizontal or vertical.
c) Determine where the curve is concave upward or downward?

I was able to do part a and b, but I'm stuck on part c. How do you find the second derivative of this curve?

That's the formula I'm having trouble understanding. But I googled some examples and I think I get it now. It's the derivative of the 1st derivative divided by the denominator of the first derivative, right?

Originally Posted by cityismine and edited (in red) by Mr F

That's the formula I'm having trouble understanding. But I googled some examples and I think I get it now. It's the derivative with respect to t of dy/dx divided by dx/dt, right?

Right.