In this thread , the instructions say to decompose: . . . . . \left<x_1,\, x_2,\, x_3,\, x_4\right>\, =\, \left<-\frac{5}{3}r\, -\, \frac{8}{3}s\, -\, \frac{4}{3}t,\, r,\, s,\, t\right> Now decompose this into three vectors multiplied by r, s, and t, and I believe you'll have your basis vectors. I'm...