Let →a,→b,→c are three non zero vectors such that any two of them are non-collinear. If →a+→b is collinear with →c and →b+→c is collinear with →a, then the value of →a+→b+→c equals
We have,→a+→b is collinear with →c
Then,→a+→b=u→c......(1)
And →b+→c is collinear with →a
Then, →b+→c=v→a......(2)
By equation (1) and (2) to, we get
→b+→c=v(u→c−→b)
→b+→c=vu→c−v→b
→b+v→b=vu→c−→c
→b(1+v)=→c(uv−1)
But given that, →b and →c are collinear.
Then, →b=0 and →c=0
Now, 1+v=0,v=−1
And uv−1=0,u×(−1)=1,u=−1
Put the value of u and v in equation (1) and (2), we get
→a+→b=(−1)→c
→a+→b=−→c
→a+→b+→c=0
Hence, this is the answer.