Below are some notes that I took while following Daniel Shiffman’s video tutorials on neural networks, which are heavily inspired by Make Your Own Neural Network, a book written by Tariq Rashid. The concepts and formulas here are not my original material, I just wrote them down in order to better understand and remember them.

### Slope and intercept

A line is traditionally represented by this equation, in which m represents the slope and b the y intercept at the origin:

In the case of linear regression (or the ordinary least squares method), we will calculate the m value with the formula below. This formula is taken from this video made by Daniel Shiffman for his Intelligence and Learning course. We will consider that the numerator of this fraction represents the correlation between the growth of the value x and the growth of the value y (which determines the slope of the line).