高数函数求极限

1.原式=lim(x→0)(x²-2x+3)/(2x³+x²+1)=3/1=3
2.原式=lim(x→0)[(1-3x)^(1/(-3x))]^[3(x-1)]
=e^{lim(x→0)[3(x-1)}
=e^(-3)=1/e³
3.原式=lim(x→0){[√(1+sinx)-√(1-sinx)]/x}
=lim(x→0){2(sinx/x)/[√(1+sinx)+√(1-sinx)]}
=2[lim(x→0)(sinx/x)]/{lim(x→0)[√(1+sinx)+√(1-sinx)]}
=2*1/2
=1
4.原式=ln{lim(x→0)[(1-2x)^(1/x)]}
=ln{lim(x→0)[(1-2x)^(1/(-2x))]}^(-2)
=ln[e^(-2)]
=-2