[问答题]
A package delivery company off
*uoc(jke1. :ot-wvh z mbsiv),,2pc aers 24 hours delivery service to a limited
lx d-f7) reeyb*+o-dhnumber of cities in close proximity. The d
eyfl7 -rehdob+* )d-x irected graph below shows four cities served (A-D) and the routes of delivery between them.
1. Find an adjacency matrix $\boldsymbol{A}$ for the shipping network.
2. Find the number of ways it is possible to ship a package from city $\mathrm{C}$ to city $\mathrm{A}$ using exactly three delivery routes.
3. (1) Find the matrix $\boldsymbol{S}_{3}$ , where $\boldsymbol{S}_{3}=\sum_{i=1}^{3} \boldsymbol{A}^{i}$ .
(2) Hence write down the number of ways it is possible to deliver a package from city A to city D using three or less delivery routes.
(3)State all possible ways to ship a package from city A to city D using three or less delivery routes.
