>>197

x/(1-x) = t-1 とおくと x = 1 - 1/t,
　t→±∞ の極限
　

a≠1 のとき
　(a^x -1)/x = {e^(x･log(a)) -1}/x
　= {e^(x･log(a)) -1}/(x･log(a)) * log(a) → log(a),