I think you forget to read:
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 Prerequisites and Requirements<p>This is an intermediate to advanced level course. Prior to taking this course, and in addition to the prerequisites and requirements outlined for the Machine Learning Engineer Nanodegree program, you should possess the following experience and skills:<p>Minimum 2 years of programming experience (preferably in Python)
Git and GitHub experience (assignment code is in a GitHub repo)
Basic machine learning knowledge (especially supervised learning)
Basic statistics knowledge (mean, variance, standard deviation, etc.)
Linear algebra (vectors, matrices, etc.)
Calculus (differentiation, integration, partial derivatives, etc.)
See the Technology Requirements for using Udacity.