1. Answer the following questions: a) Express $\boldsymbol{u}=(1,3,-1)$ as a linear combination of $\boldsymbol{u}_{1}=(1,0,0), \boldsymbol{u}_{2}=$ $(2,-2,1 $, and $u_{3}=(2,0,4)$. b) Check the linear dependency of the vectors $u_{1}=(1,2,3), u_{2}=(0,1,2)$, and $\boldsymbol{u}_{3}=(3,5,7)$. CS.JG. 117