∵ cos(8π/x) ≤ 1 (x≠0) ,e^x 单调递增；
∴ 0 < e^(cos(8π/x)) ≤ e^1 = e
∴ 0 < [(3x)^1/2] * e^(cos(8π/x) ≤ [(3x)^1/2]
∵ lim(x->0+) [(3x)^1/2] = 0 ,由夹逼定理：
∴ lim(x->0+) [(3x)^1/2] * e^(cos(8π/x) = 0