Answer to Question #57072 in Linear Algebra for jaydeb maity

Question

1. There exist vectors u & v in an inner product space such that ||u||=2,||v||=7,||u+v||=8 and ||u-v||=6. Is it true? Justify.
2. Find the dual basis of the basis {(1,-1,3),(0,1,-1),(0,3,-2)} of R.
3. If V is a vector space over K and f:V to K is a non zero linear function , then f is onto. Is it true? Justify it or give a counter example.