lim(x→∞)(x2+x)/(x4-3x2+1)的极限是多少?

lim(x→∞)(x2+x)/(x4-3x2+1)的极限求法过程 lim(x→∞)(x2+x)/(x4-3x2+1)的极限是多少? 求极限：lim（1/x2-cot2x)x→0这么做错在哪：lim(sin2x-x2cos2x)/x2sin2x=lim(x2-x2(1-sin2x))/x4=lim(x2-x2+x4)/x4=1为什么不能这么求? 求极限：lim（1/x2-cot2x)x→0这么做错在哪：lim(sin2x-x2cos2x)/x2sin2x=lim(x2-x2(1-sin2x))/x4=lim(x2-x2+x4)/x4=1为什么不能这么求?lim（1/x^2-(cotx)^2) 其中x→0 =lim((sinx)^2-x^2(cosx)^2)/（x^2*(sinx)^2)=lim(x^2-x^2(1-(sinx^2))/ lim x-∞ x2-1/3x2+x 求极限 x2-3x+1=0 x2/(x4-x2+1) 因式分解x4+x3+2x2-x+3 计算极限 lim X2-3X+2 -------------- x→2 X2+5X-6lim X2-3X+2------------x→2 X2+5X-6 x+1/x=3,求x2/x4+x2+1 lim(x→0) 1-cosx/x4次方 lim(x2-4x+5)/2x2-x-1 x→∞ 已知x+1/x=3 求x2+1/x2和1/x4+x4 T求下列函数的极限lim(x→∞)x3+2x/x2+1.lim(x→∞)(x-4/x+1)2x-1[次方lim(x→1)（1/1-x-3/1-x3). 若X2-3X+1 求x+1/x和x2+1/x2以及x4+1/x4的值若X2-3X+1=0 求x+1/x和x2+1/x2以及x4+1/x4的值 求极限lim X→∞ [1+ x2/2 -√(1+ x2)]/(cos x –e x2 )sin x2 亲 求下列的极限1.lim(x→∞）(1-3/x)'x2.lim(x→1）2x'2-x-1/x'2-13.lim(x→0）1-cosx/x'24.lim(x→∞）x'3/e'x5.lim(x→0）sin4x/x Lim(x+y)/(x2-xy+y2) (x,y)→(∞,∞)这个怎么算Lim(x,y)→(∞,∞) (x+y)/(x2-xy+y2) 10个个极限的运算求解1）lim（x-1）（3次根号下x-1）/（根号x-1)2）lim（x-∞）（x^2+1）^50/(x+1)^1003)lim(x-∞)2x+3/x+3次根号下X4)lim(x-0)sin4x/x5)lim(x-0)1-cos2x/xsinx6)lim(x-∞)[(x-1)/(x+3)]^(x+2)7)lim(x-∞)n[ln(n+3)-l