1、极限值 = 函数值； 例如：假设f(x)f(x)f(x)在[0,+∞)[0,+\infty)[0,+∞)上连续，0⩽f(x)⩽x,x∈[0,+∞)0\leqslant f(x) \leqslant x, x\in [0,+\infty)0⩽f(x)⩽x,x∈[0,+∞)，若a1⩾0,an+1=f(an),n=1,2,…a_1 \geqslant 0,a_{n+1}=f(a_n),n=1,2,…a1⩾0,an+1=f(an),n=1,2,…那么：A=limn→∞f(an)=f(limn→∞an)=f(A)A = lim_{n \to \infty}{f(a_n)} = f(lim_{n\to \infty}{a_n}) = f(A)A=limn→∞f(an)=f(limn→∞an)=f(A)
