This page contains links to some of the unusual topics included in Math A&I, topics which you may not have studied yourself!
But know that is many cases, particularly at SL level, IB tests on limited cases of these unusual topics.
If your school has a textbook specifically written for IB Math A&I, it should be a good resource.
Looking through past IB Exams is also very useful. IB releases the Exams from each session, for use in schools. Ask your coordinator if they buy the IB Exam Packs.
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Here's a collection of informational links to the topics which might have you puzzled. Speaking of which, did you know that the good old "r-value" from linear regressions is more formally titled "Pearson's Product-Moment Correlation Coefficient? And that a value close to 1 doesn't necessarily show that a linear fit is appropriate?
SL and HL:
Voronoi Diagrams Pearson's Product-Moment Significant Figures and Accuracy - ask your chem or physics colleague!
HL only:
Eigenvectors More Eigenvectors Logistic Models Adjacency Matrices Tree Algorithms Nonlinear Regression
Linear Transform of Random Variable Transition Matrices Kinematic problems including a = v*(dv/ds) Coupled First-Order Differential Equations