What is the domain of this function

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

Out of 50 students surveyed, 16 have a dog. based on these results, predict how many of the 280 students in the school have a dog.

Given the expression (7 ? 4i) ? (2 + 6i), perform the indicated operation and write the answer in the form a + bi.