The sequence is strictly monotone decreasing. Using the closed formula you can answer to question ii) and iv).
U1 =3.9, Un+1 = Un - 1.7 (n= 1,2,3,....).
i) state what type of sequence this is.
ii) write down the first four terms of the sequnce.
iii) find a closed form for the sequence.
iv) use the closed form from iii) to find the value of n when Un = - 76.