问题标题：
数学极限lim(x→0)((x^3)/(3*x^2-1))lim(x→+无穷)(√x(x+2)-√(x^2-x+1))lim(x→1)(tan(x-1))/(x^2-1)
问题描述：
数学极限lim(x→0)((x^3)/(3*x^2-1))lim(x→+无穷)(√x(x+2)-√(x^2-x+1))lim(x→1)(tan(x-1))/(x^2-1)
戴耀回答：
lim(x→0)((x^3)/(3*x^2-1))
=lim(x→0)3x^2/6x=0
lim(x→+∞)(√x(x+2)-√(x^2-x+1))=lim(x→+∞)(√(x+1)^2-1-√x-1/2)^2+3/4)
=lim(x→+∞)(x+1-(x-1/2))
=3/2
lim(x→1)(tan(x-1))/(x^2-1)
=lim(x→1)(sin(x-1)/cos(x-1)(x^2-1)
=lim(x→1)(sin(x-1)/cos(x-1)(x-1)(x+1)当x-1→0limsinx=limx
所以lim(x→1)(sin(x-1)/cos(x-1)(x-1)(x+1)
=lim(x→1)1/cos(x-1)(x+1)
=1/2
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