Question

How do you factor `x^2 - 13x +42`?

Answer 1

Note that `(x-a)(x-b) = x^2-(a+b)x+(axxb)`

Also note that `13 = 6 + 7` and `42 = 6 xx 7`

So `x^2-13x+42 = (x-6)(x-7)`