A The problem stems, I think, from the approach taken when teaching the multiplying out of the brackets. The approach I prefer is the following as it then translates to helping in the understanding of factorising quadratic expressions.
The example I shall use is (2x - 1) (x + 2). Write this as 2x (x + 2) - 1(x + 2) this is an important stage giving 2x2 + 4x - x - 2 = 2x2 + 3x - 2.
Now I will describe how this can be factorised easily:
Wendy Fortescue-Hubbard is a teacher, game inventor and member of the London Mathematical Society. She has been awarded a three-year fellowship by the National endowment for Science, Technology and the Arts (NESTA) to spread maths to the masses. Email your questions to Mathagony Aunt at email@example.com Or write to TES Teacher, Admiral House, 66-68 East Smithfield, London E1W 1BX