How do you factorise x²-4 plus 3?

Answer 1

I am thinking you must mean x^2-4x+3 otherwise it would be x^2-1 which would factor as (x+1)(x-1).
In any case, it factors as (x-3)(x-1). Just look at the last number, 3 and note it has factors 3 and 1. Now need those factors to add up to -4 and their product to be positive. We must pick -1 and -3.