Prove the identity: cos(3x) + cos(x) = 2cos(2x)cos(x)
i'm almost done with my homework, just got stuck on this one.

Cameron indoor stadium at duke university is one of the most revered sites in all of college basketball, as well as in all of sports period. duke’s men’s and women’s basketball programs have attained quite a few wins in the building over the last seventy years. cameron indoor stadium is capable of seating 9,460 people. for each game, the amount of money that the duke blue devils’ athletic program brings in as revenue is a function of the number of people in attendance. if each ticket costs $45.50, find the domain and range of this function.

The average number of vehicles waiting in line to enter a parking lot can be modeled by the function f left parenthesis x right x squared over 2 left parenthesis 1 minus x right parenthesis endfraction , where x is a number between 0 and 1 known as the traffic intensity. find the rate of change of the number of vehicles waiting with respect to the traffic intensity for the intensities (a) xequals0.3 and (b) xequals0.6.

Closing a credit card usually _your debt ratio.a. increasesb. decreasesc. improvesd. has no effect on