A day for differentiation

The necessary holiday travels and visits are done. It wasn't much this year. Now I'm back home. That's good. I kind of like these corona times. There are fewer places I need to go, less people I need to visit. More time on my own. 

I have watched some football with the boys. Last night Leeds won 5-0 against West Bromwich. 

The winter has been crappy so far. Not much snow in my part of Winterland, and the borders are closed. No skiing.

The last couple of days I have been in the office to do some fun stuff, while everybody are gone, and the bosses don't send me mails. Today I finally found the time to do some math that I needed to work my way through. Just some straight forward differentiations. But I need to be focused, to get all the signs right.

(That's the summary of what I have produced today in the picture)