note 320/400=0.8 (=256/320=...). You thus find x_n = 0.8 x_(n-1), the closed form is then given by x_n = 400*(0.8)^(n-1).
Can you do the other exercise yourself now?
(b) Consider the following geometric sequence.400,320,256,204.8,...(i)Write down a recurrence system that describes this sequence.(Denote the sequence byxn,and itsfirsttermby x1.)[2](ii) Find a closed form for this sequence.[2](iii) Use the closed form from part (b)(ii) to find the tenth term of thesequence, giving your answer correct to four decimal places.[2]