Question

lim n→0时,求(cosx-1)/x²的极限

Answer 1

lim(x-->0) (cosx - 1)/x²

= lim(x-->0) [1 - 2sin²(x/2) - 1]/x²

= lim(x-->0) - 2sin²(x/2)/(x/2)² * 1/4

= lim(x-->0) [sin(x/2)/(x/2)]² * -1/2

= -1/2