Borbin the 🐱

Here is the third one:

Option c) leads to the solution. The expression
f(x) + f(y) + x²y + xy²
is part of the expansion of the binomial
(x+y)³
If f(x) corresponds to the first or last term of the binomial expansion, the equation can be solved.

Here is the second one:

Start by moving the x term to the right-hand side and setting x=0. This is the first equation for b.
Then with b in place, get the second equation. Isolate a and substitute 0 for x. This gets

I've been helping out with high school math lately, and some of the questions are quite interesting.
Check this one out:

The key is to derive two equations from the derivative. With a fourth-degree polynomial, we get three points where the slope is the same, but only two of them share a common tangent line.
After that, everything falls into place.

August 21st 2017
Sun Eclipse over North America

Using the Optrel Weldcap to watch the sun eclipse seemed like a great idea.

Worked great to begin with, but unfortunately the Weldcap failed after 10min and the auto darkening switched on and off.
Weldcrap! This was quite a unsafe experience. Best thing to do was this:

Here is another¹ example of modern engineering excellence. Looks great from the outside but not so much from the inside.
(¹ Samsung Dishwasher: Looks nice, but has an astonishing accuracy to start failing past the end of the warranty. A great marvel of Korean engineering.)

See for yourself:

Once the stick is powered up, you have to wait several minutes until you get a response. Instantly pressing a button on the control when the start screen is coming up makes the device unresponsive. Very annoying.
Bonus: You get nice different themes during start.

Or: Switch sub titles on/off. Great solution presented here too. Once you decide to change sub titles in the middle of the presentation, you have to go back to the main menu and start all over.

After a few weeks of use, I discovered that the batteries were empty. Replaced then and did not gave this a thought, until a few weeks later the batteries were empty again. It was not obvious that the batteries were empty since the device does not respond instantly anyway but a quick check with the multi meter confirmed it.
When did you replaced the last time the batteries of your remote?

I contacted Roku support about all this along with the confirmation that I did all the steps the FAQ suggests, only to get an answer one week later to go and check the FAQ. Report ticket was automatically closed. How convenient.

Checked the remote for power consumption:

Almost 12mA current is drawn constantly. No key is pressed!
I'm surprised the batteries made it that long.

Compared this to my WD Media Player remote:

and 0mA, the way a remote should work.

Checked the Roku remote control inside, but decided not to waste any more time.

And here is my solution:

Hi,

You received this email because you requested to close your account, we have removed your information from our system.

Thanks for using Roku!

Roku