Find a subset of u₁​,u₂​,u₃​,u₄​ that gives a basis for W=Span{ui​} of R⁵, where
u₁​=(1,0,1,0,1),u₂​=(1,1,2,1,0),u₃​=(2,1,3,1,1),u₄​=(1,2,1,1,1)