a. PQ→=⟨−4,−1,2⟩\overrightarrow{PQ}=\lang −4,−1,2\rangPQ=⟨−4,−1,2⟩> b. PQ→=−4i−j+2k\overrightarrow{PQ}=−4\bold{i}−\bold{j}+2\bold{k}PQ=−4i−j+2k