(a) Find the position vector of a particle that has the given acceleration and the specified initial velocity and position.
(b) Graph the path of the particle.
$$\mathbf{a}(t)=t \mathbf{i}+e^{t} \mathbf{j}+e^{-t} \mathbf{k}, \quad \mathbf{v}(0)=\mathbf{k}, \quad \mathbf{r}(0)=\mathbf{j}+\mathbf{k}$$