The path is a straight line from $(1,1)$ to $(2,3)$. The direction vector of this line is $(2-1,3-1)=(1,2)$. Therefore, the parameterization of the line is given by $\mathbf{r}(t) = (1+t)\mathbf{i} + (1+2t)\mathbf{j}$ where $0 \leq t \leq 1$. The derivative of
Show more…