1 Guessing the answers. Pros If you guess well, then easy to solve. Cons Hard to show your working. Only works for really simple ones. Can take a lot of time.
2 By adding/subtracting equations (traditional method) Pros Works for all but the most complicated equations( A – level). Will give exact answer. Cons Need to show all working and work carefully. May need to multiply equations first
3 Graphically Pros Will work every time Works for families of equations Cons Not always accurate Time consuming Long-winded, lots of room for mistakes to creep in.
4 Substitution Pros Can be quickest way Best way for complicated equations e.g.. powers Cons Not suitable for all equations More likely you are looking at A – level paper.