How to factorize the quadratic equations fast?

[Guest]

Hi,

I know that to factorize a quadratic equation, we need to find a pair of numbers which should be the product of the last term and also add up to the number in the middle term. However for large numbers how can we systematically find such a pair which will satisfy both requirements?

[Guest]

If I could see no obvious connections between factors of the coefficients, I would set the quadratic equal to 0 and solve using either "completing the square" or the "quadratic formula".