On 9/8/99, downeyad asks about Q14 of MA322-005,Section 2.6 and 2.7: I do not understand this at all.font> Response: Sorry, neither of the alternatives listed is the answer. But I fixed it. Try again.

On 9/8/99, downeyad asks about Q15 of MA322-005,Section 2.6 and 2.7: please go over this in class Response: Yes. You can see this by using the facts that x dot y = x^T y and (ab)^T = b^T a^T.

On 9/21/99, kendigbr asks about Q15 of MA322-005,Section 2.6 and 2.7 (Sept. 20): I thought maybe this was written wrong otherwise could you go over it. Response: See the above response. As we mentioned in class, the identity Ax dot y = x dot A^T y is especially important when Ax dot y is 0.

On 9/21/99, kendigbr asks about Q7 of MA322-005,Section 2.6 and 2.7 (Sept. 20): Still a little hazey about how to do this, the previous hint wasn't much help. Response: We worked this out in class. Carry out the first elimination and get a 3 - 2c in the 2,2 spot. that's 0 when c = 3/2. Then assume that 3 - 2c is not 0 and carry out the next two eliminations and get a (3-c)/c in the 3,3 spot. Note: These are the values for c you get if no row interchanges are performed.

On 9/21/99, kendigbr asks about Q8 of MA322-005,Section 2.6 and 2.7 (Sept. 20): Could you cover this one also. Response: Just carry out the elimination steps. You are led to solve two equations: a^2 -1 = 0 and 2*a^2 - 1 = 0.

On 9/21/99, kendigbr asks about Q9 of MA322-005,Section 2.6 and 2.7 (Sept. 20): Not sure what they meant. I couldn't follow it. Response: One way to work on this is to write out the matrix A A^T for the case A is 2 by 2. Set this equal to the 0 matrix and look at the equations.