Derivation

 Found this useful table of derivatives:

https://fr.wikipedia.org/wiki/Table_de_d%C3%A9riv%C3%A9es_usuelles

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On the inflation front, the CPI for April 2023 was at 156.4, up .7

from March.

https://www.lapresse.ca/affaires/economie/2023-05-16/l-inflation-repart-a-la-hausse-en-avril-au-canada.php

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Found an example of gradient descent on a linear regression:

Machine Learning Fundamentals: Cost Function and Gradient Descent | by Anmol Tomar | Geek Culture | Medium