How do you factorise quadratic, cubic functions or even quartic functions?

Start by trying to find a common multiple of the last term, e.g. if you have a quadratic that ends in 4, when you factorise this function, we should get two terms ending in multiplies of 4 so (1,4) or (2,2). This is the exact same for a cubic function, however, factorising it once leaves a quadratic that we may or may not be able to factorise. The most appropriate method is the bus method, the same method you would use for normal division can be applied to cubics and even quartic functions.