I recently went to see the film x+y, which is really about autism, but centred on an autistic teenager who enters the Mathematical Olympiad, an international competition for high school students.

# Monthly Archives: March 2015

# S2 test paper, 26-27 March 2015

# D1 test paper, 26-27 March 2015

# M2 test paper, 26-27 March 2015

# D1: collections of questions from past papers, by topic and by date

**By topic**:

- Chinese postman
- Critical path analysis, Gantt charts, scheduling
- Dijkstra
- Kruskal and Prim
- Linear programming
- Matchings
- Sorting and binary search

**By date**

- D1 papers and answer books 2014-2013 (I recommend that as you do each paper, you neatly tear out the question paper so that you can have question paper and answer book separate in front of you)
- Mark schemes for those 2014-2013 papers
- D1 papers and answer books 2012-2010 (I recommend that as you do each paper, you neatly tear out the question paper so that you can have question paper and answer book separate in front of you)
- Mark schemes for those 2012-2010 papers

# Why is the rule as it is for inverting 2×2 matrices?

The inverse of the 2×2 matrix

a b

c d

is

d −b

−c a

divided by the determinant, ad−bc Continue reading