Lessons for Topic 4.11
Computing a determinantMultiply the diagonals and subtract.Lesson
What the determinant meansIt is the area or volume scaling factor, and zero means the matrix flattens everything.Lesson
Inverse of a 2 by 2 matrix, and solving with itSwap, negate, divide by the determinant.Lesson
When a matrix or transformation can be undoneA matrix can be undone exactly when nothing but zero lands on zero, which is when its determinant is not zero.Lesson
Matrix multiplicationEach entry is a row of the first dotted with a column of the second.Lesson