underset(lim)(x→0)(sin3x)/(2x)的值等于 ____ ．

(3) lim _(xarrow 0)dfrac (sin 2x)(sin 5x);

求极限；（3）lim _(xarrow 0)dfrac (sin 2x)(sin 5x)；求极限；（3）；

设lim_(x to 0) (sin 2x + xf(x))/(x^3) = 1，则lim_(x to 0) (2cos x + f(x))/(x^2) = (

[题目] lim _(xarrow 0)(dfrac (1)({sin )^2x}-dfrac ({cos )^2x}({x)^2})= __

8.设lim_(x to 0) (sin 2x + xf(x))/(x^3) = 1,则lim_(x to 0) (2cos x + f(x))/(x^2) =

(3) lim _(xarrow 0)dfrac (1-cos 3x)({sin )^2x}

求极限lim _(xarrow 0)(dfrac (1)({sin )^2x}-dfrac ({cos )^2x}({x)^2})= ()求极限

[题目]求 lim _(xarrow 0)(dfrac (1)({sin )^2x}-dfrac ({cos )^2x}({x)^2})

[题目]求 lim _(xarrow 0)(dfrac (1)({sin )^2x}-dfrac ({cos )^2x}({x)^2})

填空题.lim _(xarrow 0)dfrac (arcsin 2x)(sin 2x)=填空题.