What Is the reason for AC=AB+BC ?​

Using the quadratic formula find the zeros of the given polynomial -5x^2+3x-11

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online

What is coefficient of the term of degree of degree 5 in the polynomial below