The common ratio is the common multiple of consecutive terms, usually denoted as "r" for the common ratio. Mathematically the common ratio is a constant that one finds when any term is divided by the term preceding it, in this case:
We have to rewrite the expression so that it has no denominator. For example: 1 / x = x^(-1) 1/8 = 8^(-1); 1/x^(4) = x^(-4); 1/y^(3) = y^(-3); 1/z = z^(-1).