Is it possible to factor #y=x^2+9x+28#? If so, what are the factors?
You are trying to find factors of 28 which add together to give 9.
the factor pairs of 28 are 1x28, 2x14, 4x7. These factor pairs add to give 29, 16 and 11 respectively.
Hence there are no factors which meet the requirements and this expression cannot be factorised.