Paul Homework 5

Great Work!

2. Good! Just need to check you got the definition down. 3. Haha, I forgot the shorthand for solving for the nullspace, thanks! I will use that in the lecture today. 4. Good! Haven't checked the work, but I see that it has a span of some vector (most likely the nullspace) plus some particular solution. This is because is Ax=b and Ay=0, A*(x+y)= Ax + Ay = b+0=b. 5. Cute! I see, you used the cosine formula for each vector and found your own system of equations. Nice! 6a. Good effort, but we cannot use the same mnemonic. I will show in lecture today. 17. YES! It must have a row of zeros in its reduced echleon forms. Didn't realize this: I kinda cheated and said, determinant of A is 0 since that is equivalent to being singular. det(AB)= det(A)*det(B)=0*det(B)=0. The things I forget in my old age... 2,3,4. Good. Every math major must compute a matrix inverse once in their life. Real math major also deal with right and left inverses, so great!