$9\mathrm{.}15$ a$.$ Find a minimum spanning tree for the graph in Figure $9\mathrm{.}84$ using both Prim's and Kruskal's algorithms.

b$.$ Is this minimum spanning tree unique? Why?

$9\mathrm{.}16$ Does either Prim's or Kruskal's algorithm work if there are negative edge weights? Please nust answer $15$ and $16.$ Ignore the rest of the question

Figure $9\mathrm{.}84$ Graph used in Exercise $9\mathrm{.}15$