5. Find \( \int_C \vec{F} \cdot d\vec{r} \), where \( \vec{F} = \ln y \vec{i} + \ln x \vec{j} \) and C is the curve given parametrically by \( (2t, t^3) \) for \( 2 \le t \le 4 \).
6. Find \( \int_C \vec{F} \cdot d\vec{r} \), where \( \vec{F} = -y\vec{i} + x\vec{j} + 5\vec{k} \) and C is the helix \( x = \cos t \), \( y = \sin t \), \( z = t \) for \( 0 \le t \le 4\pi \).