Bất phương trình: 3 2 2 2 − + −  + − x x x x
có tập nghiệm là
A.
12; . B.
(12; . C.
(1;+). D.
(12; ) .

Jabari is power washing houses for a summer job. for every job, he charges an initial fee plus $30 for each hour of work. his total fee for a 4 -hour job, for instance, is $170 . jabari's total fee,f, for a single job is a function of the number,t, of hours it takes him to complete the job. write the function's formula.