Video narration
You pick factors of the last term to split the middle, but the brackets won't match. You missed the leading coefficient. For ax2 plus bx plus c, your pair must multiply to ac and add to b. That's the ac method: product ac; sum b. Take six x squared plus eleven x plus three. Six times three is eighteen. Nine and two multiply to eighteen and add to eleven. Split eleven x into nine x plus two x: six x squared plus nine x plus two x plus three. Group as six x squared plus nine x, and two x plus three. They become three x times the bracket two x plus three, plus one times that same bracket. So the factors are three x plus one and two x plus three. Expand to check: six x squared plus eleven x plus three. If no integer pair passes both checks, this method won't give integer factors. Keep the rule: check both, then split, group, and factor.