Question

Which of the following os false?

a. Suppose a vector y is orthogonal to vectors u and v. Then y is orthgonal to every vector in Span{u,v}

b. suppose u, v and w are vectors in R^3. If u is orthogonal to v and v is orthogonal to w than u must be orthogonal ot w

c. If M is an orthogonal matrix then u.v = (Mu).(Mv) for any vectors u and v.

d. A matrix M is orthogonal if and only if M^T=M^-1