Exercise 6.B.11

Suppose ⟨⋅,⋅⟩ 1 and ⟨⋅,⋅⟩ 2 are inner products on V such that v , w 1 = 0 if and only if v , w 2 = 0 . Prove that there is a positive number c such that v , w 1 = c v , w 2 for every v , w V .