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问题: limx^2-1/sin(x+1)

lim[x,-1]

解答:

limx^2-1/sin(x+1) x→ -1
∵-(1)^2-1=0,sin(-1+1)=0
∴limx^2-1/sin(x+1) x→ -1 是0/0未定式
根据罗必塔法则
limx^2-1/sin(x+1) x→ -1
等价于:
lim(x^2-1)ˊ/sin(x+1) ˊ x→ -1
=lim2x/cos(x+1) x→ -1
=2*(-1)/coc(-1+1)
=-2/cos0
=-2