Find -3a+6b matrices i don’t understand how to solve these with an equation (-3a+6b)

If the discriminant if a quadratic equation is 4 which statement describes the roots?

The evening newspaper is delivered at a random time between 5: 30 and 6: 30 pm. dinner is at a random time between 6: 00 and 7: 00 pm. each spinner is spun 30 times and the newspaper arrived 19 times before dinner. determine the experimental probability of the newspaper arriving before dinner.

Factor the polynomial by its greatest common monomial factor.