12-240/Classnotes for Thursday November 8

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Riddle Along

Four cars drive in the Sahara desert at constant speeds and with constant directions. A meets B, C, D; B meets C, D. Do C and D meet?

Goals

1. compute Rank T over A
2. Compute [math]\displaystyle{ T^{-1} }[/math] over [math]\displaystyle{ A^{-1} }[/math]
3. Solve systems of linear equations

Theorems

1. Given V' -> V -> W -> W' (where the linear transformations are Q, T, P respectively)
such that P and Q are invertible (i.e. Q is surjective and P is injective) then rank T = rank PTQ

2. if T: V -> W, V with basis [math]\displaystyle{ \beta }[/math] and W with basis [math]\displaystyle{ \gamma }[/math] rank [math]\displaystyle{ [T]_\beta^\gamma }[/math] = rank T

3. if P and Q are invertible matrices, A is some other matrix, rank A = rank PAQ

Definitions

if A = [math]\displaystyle{ M_(m \times n) }[/math], then it is linear transformation [math]\displaystyle{ T_A : F^n -\gt F^m }[/math]

Lecture notes upload by yaaleni.vijay