A sequence is defined by the formula fn+1=fn−3. If f4=22, what is f1?10133134

Answer:31We can actually solve the problem by using a reverse approach. In fact, our sequence is defined by\(f(n+1) = f(n)-3\)So we can rewrite it as\(f(n) = f(n+1)+3\)For n = 3, we get:\(f(3) = f(4) +3 = 22 +3 = 25\)where we used the information that we already knew, \(f(4) =22\).Now we simply use this approach to find all the terms until f(1):\(f(2) = f(3) +3 = 25 +3 = 28\)Finally\(f(1) = f(2)+3=28+3=31\)