lim （x^3+2x-1）/（2x^3+x^2-2）x趋于正无穷,怎么算?

lim(2x-3/2x+1）^x+1 1、lim(x->无穷大) e^x arctanx2、lim(x->0)sinx√1+sin(1/x)3、lim(x->无穷大)【（√x^2+x+1）-【(√x^2-x+1)】4、lim(x->无穷大)((x+{x+(x)^0.5]^0.5}^0.5)/(2x+1)^0.55、lim(x->0)(sin3x+x^2sin1/x)/((1+cosx)x)6、lim(n->无穷大)(2^n)(si lim(x->无穷大){(2^x-3^x)/2}^(1/x) lim(x->0)((2-x)/(3-x))^1/x lim（x-3/x+1）^x lim趋向无穷大 1.lim x->∞ （2x/x^2+1)*cosx 2..lim x->∞{ [(x^2-x)arctanx]/x^3-x-5}3..lim x->0 （e^x-e^-x-2x)/(x-sinx) 4..lim x->0 (sinx-x)/(x^3) 5..lim x->0 (x^2*tanx)/(x-tanx) 6..lim x->0 (1+3/x)^2x 7..lim x->0 (1+2x)^(3/sinx) 8.lim x->∞ (x/1+x)^(x-3) 9..li lim(x->+∞）[3^x+2^x]/[(3^x+1)+(2^x+1)] lim（x^2-2x+1）/（x^3-x）的极限,x趋于1 Lim (1+x)(1+2x)(1+3x)-1除以x （x趋向0） lim √（3-x）-√（1+x）/x平方+x-2x→1 lim(x+1)^x+1(x+3)^x+3/x^2x+4 x趋于无穷 用罗必达法则解 （见图）lim [(e^x)-1/sin（5x)]x->0lim [1-cos(5x)/1-cos(7x)]x->0lim x->0 [(8^x-7^x-1)/(x^2)-1]lim [1-(6/x)]^x x->∞ lim 7cos(3x)sec(9x)x->pi/2 数学难题,求指教~~极限到底是什么玩意我还不懂.1.lim（x^2-2x+6）2.lim(x^2-4)/(x-2）3.lim(x^2-6x=8)/(x^-5x=4)4.lim[1/(1-x)-1/(1-x^3)5.lim(sin2x)/x^26.lim(sin5x)/x7.lim(tan3x)/(sin7x)8.lim[(1+x)/x]^2x例如这道例题~lim[(1/3)x+1] lim(2x+3/2x+1)^(x+1) 求极限lim(1-2/x+3/x^2)^x lim(x->2) {(3x+16)^1/2-4}/x 极限lim(x^2+2x+3)/(x-1) lim x->无限大 (1+1/2x) ^ 3x+lnx