nth Term of an Arithmetic Progression     Let …….. be an A.P., with first term as a, and common difference as d.     First term is         = a            (i)     Second term     = a + d            (ii)                 =     Third term         =         (iii)                 =      [from (i)]                 =         or         =     Fourth term         or          =      [from (iii)]                  =                 …

Sequence and Series   Sequence: A sequence is an arrangement of number in a definite order, according to a definite rule. Terms: Various numbers occurring in a sequence are called terms or element.     Consider the following lists of number:         3, 6, 9, 12, ……………         4, 8, 12, 16, ……………         -3, -2, -1, 0, ……………     In…