What value, in place of the question mark, makes the polynomial below a perfect square trinomial? x2 - 28x + ?

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.2 days and a standard deviation of 1.7 days. what is the probability of spending more than 2 days in recovery? (round your answer to four decimal places.)

In triangle abc, w is the centroid and be = 9. find bw. a. 3 b. 6 c. 9 d. 18