(1 point) Are the following statements true or false? ? 1. If W is a subspace of R" and if v is in both W and W, then v must be the zero vector. ? in R". ? 2. If an n xp matrix U has orthonormal columns, then UUTx = x for all x 3. If y = Z1 Z2, where Z₁ is in a subspace W and Z₂ is in W¹, then Z₁ must be the orthogonal projection of y onto W. ? 4. The best approximation to y by elements of a subspace W is given by the vector y - projw(y). ? 5. Let u₁, U2, ..., u,, be an orthonormal basis of a vector space V. In the Orthogonal Decomposition Theorem, each term p = (b, u₁)u₁ + + (b, u,)u, is itself an orthogonal projection of b onto a subspace of V.