(a) Sketch the vector field $\mathbf{F}(x, y)=\mathbf{i}+x \mathbf{j}$ and then sketch some flow lines. What shape do these flow lines appear to have?
(b) If parametric equations of the flow lines are $x=x(t)$, $y=y(t)$, what differential equations do these functions satisfy? Deduce that $d y / d x=x$.
(c) If a particle starts at the origin in the velocity field given by $\mathbf{F}$, find an equation of the path it follows.