(iii) 1, 3, 7, 15, 31, .... (1 mark)
Sol. t1 = 1
t2 = t1 + 2 = 1+ 2 = 3
t3 = t2 + 4 = 3 + 4 = 7
t4 = t3 + 8 = 7 + 8 = 15
t5 = t4 + 16 = 15 + 16 = 31
t6 = t5 + 32 = 31 + 32 = 63
t7 = t6 + 64 = 63 + 64 = 127
t8 = t7 + 128 = 127 + 128 = 255
t9 = t8 + 256 = 255 + 256 = 511
∴ The next four terms of the sequence are 63, 127, 255 and 511.
