Well, i have two problems, and i'm not really sure if the first is derivitive or not. Please help!

1. At time t a particle is moving along the x-axis is at position x. The relationship between t and x is given by tx = x(squared) + 8. At x = 2, the velocity of the particle is:

A. 1 B. 2 C. 6 D. -2 E. -1

I don't know what to do here. I tried just plugging 2 into the equation, solving to t, and doing velocity equals distance over time, but that didn't work.

2. If x(squared) + 2xy - 3y = 3, dy/dx of x = 2 equals:

A. 1 B. 2 C. -2 D. 10/3 E. -1

I tried the product rule of 2x and y, but it didn't work out right.

Thanks in advance guys!

Actually there is another problem that's even harder

If d/dx of f(x) = g(x) and d/dx of g(x) = f(3x), then d(squared)/dx(squared) of f(x(squared)) equals:

A. 4x(squared)f(3x(squared)) + 2g(x(squared)) B. f(3x(squared)) C. f(x^4) D. 2xf(3x(squared)) + 2g(x(squared)) E. 2xf(3x(squared))

I'm pretty sure its not B or C, but i really have no idea how to do this problem. My teacher did mention using the chain rule as a hint, but i stil really don't get it.