MathematicsHard210×since 2002Q3284If limn→∞ 1a+2a+......+na(n+1)a−1[(na+1)+(na+2)+.....+(na+n)]=160\mathop {\lim }\limits_{n \to \infty } \,\,{{{1^a} + {2^a} + ...... + {n^a}} \over {{{(n + 1)}^{a - 1}}\left[ {\left( {na + 1} \right) + \left( {na + 2} \right) + ..... + \left( {na + n} \right)} \right]}} = {1 \over {60}}n→∞lim(n+1)a−1[(na+1)+(na+2)+.....+(na+n)]1a+2a+......+na=601 for some positive real number a, then a is equal to :A7B8C152{{15} \over 2}215D172{{17} \over 2}217Check answerSkip