# Homework Help: Calc III help

1. Feb 21, 2009

### mamma_mia66

1. The problem statement, all variables and given/known data
Given $$\vec{}$$r"(t)= 6i-4cos (2t)j+ 9e3tk,
r'$$\vec{}$$ (0)= 4i +3k and r$$\vec{}$$(0)=j+k, find r$$\vec{}$$(t).

2. Relevant equations

3. The attempt at a solution

I will appreciate any ideas how to start this problem. Thank you.

2. Feb 21, 2009

### Unco

If r(t) = x(t)i + y(t)j + z(t)k, then r''(t) = x''(t)i + y''(t)j + z''(t)k.

How you would you normally solve x''(t)=6 for x(t), given x'(0) and x(0) ?

What is troubling you?

3. Feb 21, 2009

### mamma_mia66

I get it now. I need to integrate the given. Thank you.