limx趋向于2时,(x^2-3x-5) 如何计算?

计算极限：limx趋向于无穷,[（5x^2+1）/(3x-1)]sin1/x limx趋向于0(2x-1)^5/((2x+1)^2(1-3x)^2) limx趋向于无穷时4x^3-2x+8/3x^2+1 limx趋向于无穷x^2+2x-4/x^3-x^2 limx趋向于-1(3x^2-5x-2)/（4x^2-2x+1）的极限 求极限limx趋向于1x^2+2x+5/x^2+1 limx趋向于无穷2x^2-4/3x^2-x 求极限limx趋向于无穷大(2x+2/2x+3)^x求详细过程. limx趋向于0,x^2/ln(1-3x)=? 求极限,limx趋向于正无穷ln(1+3^x)/(1+2^x) limx趋向于0,k(1+3x))^-2/x (k为常数.求极限 limx趋向于0[xsin(3/x)+tanx/2x]的极限