a. r=⟨−3,5,9⟩+t⟨7,−12,−7⟩,t∈R \bold{r}=\lang −3,5,9\rang+t\lang 7,−12,−7\rang, t\isin\Realsr=⟨−3,5,9⟩+t⟨7,−12,−7⟩,t∈R b. x=−3+7t,y=5−12t,z=9−7t,t∈Rx=−3+7t,y=5−12t,z=9−7t, t\isin\Realsx=−3+7t,y=5−12t,z=9−7t,t∈R c. x+37=y−5−12=z−9−7\frac{x+3}{7}=\frac{y−5}{−12}=\frac{z−9}{−7}7x+3=−12y−5=−7z−9 d. x=−3+7t,y=5−12t,z=9−7t,t∈[0,1]x=−3+7t,y=5−12t,z=9−7t, t\isin[0,1]x=−3+7t,y=5−12t,z=9−7t,t∈[0,1]