贝努利不等式:若x-1,n∈N且n≥2,则(1+x)n≥1+nx.当且仅当x=0时,等号成立.若在此不等式中,令t=1+x,就可得变式:若t0,n∈N且n≥2,则tn≥n(t-1)+1.当且仅当t=1时,等号成立.下面给出上述变式的一些应用,供读者参考.例1(《上海中学数学》1999年第2期问题与解答)设α,β,λ为锐角, The Bernoulli inequality: (1 + x) n≥1 + nx if x-1, n∈N and n≥2 If and only if x = 0, the equal sign holds. In this inequality, if t = 1 + x, we can get the following change: if t0, n∈N and n≥2, then tn≥n (t-1) +1. Equal sign is true if and only if t = Some of the above variants of the application, for readers reference .Example 1 (“Shanghai High School Mathematics” 1999 the second issue and answer) Let α, β, λ for the acute angle,