如何证明lim(sin((n+1)^(1/2))-sin(n^(1/2)))=0

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如何证明lim(sin((n+1)^(1/2))-sin(n^(1/2)))=0
如何证明lim(sin((n+1)^(1/2))-sin(n^(1/2)))=0

如何证明lim(sin((n+1)^(1/2))-sin(n^(1/2)))=0
sin((n+1)^(1/2))-sin(n^(1/2)) = 2sin[((n+1)^(1/2) - n^(1/2))/2]* cos[((n+1)^(1/2) + n^(1/2))/2]
因为|cos[((n+1)^(1/2) + n^(1/2))/2]|≤1,
sin[((n+1)^(1/2) - n^(1/2))/2]=sin[1/2 * 1/((n+1)^(1/2) + n^(1/2))]→0,n→∞,
所以sin((n+1)^(1/2))-sin(n^(1/2))→0,n→∞.

极限的代换,或者用定义,重要极限运用