Finding arc.. someone help.

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Atemperature of 1.64◦f corresponds to answer in units of ◦c.

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.