题目

Computer programmer David Jones earns $35.000 a year designing new computer games. yet he cannot find a bank ready to let him have a credit card（信用卡）.Instead he has been told to wait another two years until he is 18. The 16-year-old works for a small firm in Liverpool where the problem of most young people of his age is finding a job .David’s firm releases（推出）two new games for the fast growing computer market each month But David’s biggest headache is what to do with his money. Even though he earns a lot he cannot drive a car, take out a mortgage（抵押贷款）,or get （本大题12分） 设函数f（x）= –cos2x–4tsincos+2t2–3t+4，xÎR，其中|t|≤1，将f（x）的最小值记为g（t）。 （1）求函数g（t）的表达式； （2）判断g（t）在[–1, 1]上的单调性，并求出g（t）的最值。