Had a linear algebra exam this morning. I was doing well up to the last problem when I got stuck. You’ve had that happen haven’t you? Something gets stuck in the cogs in your brain and higher order thinking grinds to a halt. You see the page, you are aware of the problem and you know, somewhere in the recesses of your mind, is the answer you seek, if only the gears would start turning. Time ran out on me this morning and not more than 10 minutes after turning in my test the wheels, as if freed from their obstruction, start spinning rapidly and I see, oh so clearly, the answer I needed 10 minutes earlier. All I had to do was swap rows 1 and 3, then I could get the whole mess of a matrix down to reduced row echelon form and find the correct inverse. D’oh!