Question:What are "Kyle numbers"?

Answer:
The book (and especially the solution book) mentions Kyle numbers.
They are a short cut to compute the kernel, especially for 2 times
2 matrices. If a 2 x 2 matrix is not invertible, the two columns have
to be parallel. For
A =  2 4 
 4 8 
for example, we see that the second column is 2 times the first column.
The Kyle numbers are 1, 2 because adding the first to 2 times the second
column gives zero. So that [1,2]^T is in the kernel.
Its better to stick to row reduction to compute the kernel since it is
easy (especially for larger matrices) to get only part of the kernel.
