x2+11x+28 I have no clue how to factor them, but I know how to find a,b, and c.
What you want to do, is get the product of (x + a)(x + b) to equal x2 + 11x + 28.
If you multiply (x + a)(x + b), this equals x2 + ax + bx + ab = x2 + (a+b)x + ab.
Therefore. a+b = 11, and ab = 28. What numbers multiply to equal 28 and add to equal 11?
Try 7 and 4. therefore x2 + 11x + 28 = (x + a)(x + b) = (x + 4)(x + 7).
If this had been x2 + 5x - 6, I would ask what numbers multiply to equal 6 and subtract to equal 5.
Try 6 and 1. Therefore x2 + 5x - 6 = (x + a)(x + b) = (x + 6)(x - 1). Note that the product gives (a + b) as
-x + 6x = 5x, the middle term. Always multiply be sure the factors are correct.
I hope this helps.