Determine whether the vector w 3 5 1 is in the span of the
     Determine whether the vector w = (3, 5, 1) is in the span of the following vectors:  v_1 = (1, 1, 1), v_2 = (2, 3, 1), v_3 = (0, -1, 1) 
  
  Solution
2v_1-v_2=(0,-1,1)=v_3
So the vectors are linearly dependent
So if w is to be in the span of the given three vectors then it must also be in the span of v1 and v2
Let, w=av1+bv2
(3,5,1)=a(1,1,1)+b(2,3,1)
3=a+2b
5=a+3b
1=a+b
Solving gives:a=-1,b=2
So,
w=-v1+2v2

