In the infinite sequence a1,a2,a3,.....aN each term after the first is equal to twice the preceding term. If a5-a2 = 12 then what is a1? I answered this correct but I feel that too much time was spent plugging in each answer so I can backsolve and I could have done with the time for the last two questions. What is the quickest way to solve this please?
4
24/7
2
12/7
6/7
4
24/7
2
12/7
6/7
