# Zero Cool

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4

1. ## Derivative problem from old book, is the answer a typo, if not, why not?

Ok, so p = 2, and not 8, but since they are multiplied, that doesn't make sense to me. I have been out of school for a long time. Now (book is 75years old), would we use some parenthesis or something to show the 2 and the 4 are separate entities?
2. ## Derivative problem from old book, is the answer a typo, if not, why not?

This problem is from the book Calculus Made Easy by Silvanuws P. Thompson, copyright 1946 (3rd Ed.) How on earth is answer not du/dt = 8u7? The author uses a dot for showing both multiplication and as a divider between the ones column and the tenths column (see pics) Thx
3. ## help with engineering/math riddle

Thank you, I will look into those suggestions.
4. ## help with engineering/math riddle

I received an email from a man who uses a unique message in his signature. It is in the form of a math equation. To the left of the equal sign is SW. I did some brief checking online and did not find an equation using SW. I don't want to publish the entire equation so that someone else solves the message before me. Any help would be appreciated. Possible clues: 1. he is a "petrophysical advisor" who works with an engineering firm 2. the equation is next to a picture of an oil derrick If you have an idea what the equation might be used for but need an extra hint, I will provide more information. Thank you.
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