Question

1当x趋于0时对(1/sinx－1/x)的极限 2当X趋于无穷时 ln(1+1/x)除以π/2 -arctanx的极限

Answer 1

1.原式=lim(x→0)(x-sinx)/(xsinx)=lim(x→0)(x-sinx)/x^2=lim(x→0)(1-cosx)/(2x)=lim(x→0)sin^2(x/2)/x=lim(x→0)(x/2)^2/x=0

2.原式=lim(x→∞)1/(1+1/x)*(-1/x^2)/(-1/(1+x^2))=lim(x→∞)(x^2+1)/(x^2+x)=lim(x→∞)(1+1/x^2)/(1+1/x)=1

3.写错了吧,上面的极限为-1,下面的极限为0,所以极限是无穷大,也就是没有极限.