1x252, 2x126, 3x84, 4x63, 6x42, 7x36, 9x28, 12x21, 14x18,
The value of the nth term of an Arithmetic Progression is given by a + (n - 1)d, where a is the first term and d is the common difference.t5 = a + (5 - 1)d = a + 4d = -1/2t9 = a + (9 - 1)d = a + 8d = -1/128Subtracting the first equation in bold from the second equation gives :-4d = -1/128 - (-1/2) = -1/128 -(-64/128) = 63/128 therefore d = 63/(128x4) = 63/512Substituting for d in the first equation a + (4x63)/512 = -1/2 : a = -1/2 - 252/512 = -508/512.t3 = -508/512 + (3 - 1)63/512 = -508/512 + 126/512 = - 382/512 = -191/256