tan3x+sinx

纪贞泡3288解 limx趋于0 tan3x/sin8x 和 limx趋于0 (x+xcosx)/(sinxcosx) -
窦苏钥17196078040 ______ lim(x→0) tan3x/sin8x =lim(x→0) 3x/(8x) =3/8 lim(x→0) (x+xcosx)/(sinxcosx) =lim(x→0) (x+xcosx)/x =lim(x→0) (1+cosx+xsinx) =2

纪贞泡3288求y=tan3xcosx的微分 -
窦苏钥17196078040 ______ y'=(tan3x)' cosx+tan3x(cosx)'=3(sec3x)^2 cosx-tan3x*sinx dy=[3(sec3x)^2 cosx-tan3x*sinx]dx

纪贞泡3288证明tan3x/2 - tanx/2=2sinx/(cosx+cos2x) -
窦苏钥17196078040 ______ tan3x/2-tanx/2 =(sin3x/2)/(cos3x/2) - (sinx/2)/(cosx/2) =(sin3x/2*cosx/2 - sinx/2 * cos3x/2 )/(cos3x/2*cosx/2) =sin(3x/2 - x/2)/[1/2(cos(3x/2+x/2)+cos(3x/2-x/2)] =2sinx/(cos2x+cosx)

纪贞泡3288lim(tanx/tan3x)当x趋于无穷大时的极限 -
窦苏钥17196078040 ______[答案] 该极限不存在 首先定义域就不是实数域,因此x趋于无穷时原极限不总是有意义的; 其次就算该极限总是有意义,那么 原式 =lim(x->∞)(sinx/cosx)/(sin3x/cos3x) =lim(x->∞)sinx*cos3x/(cosx*sin3x) =lim(x->∞)(sin4x-sin2x)/(sin4x+sin2x) =lim(x->∞)(2cos2x-1...

纪贞泡3288Y=X的tanx次方+(sinX)的x次方. -
窦苏钥17196078040 ______[答案] y=x^tanx+(sinx)^x 先这样, x^tanx=e^(Inx*tanx) (sinx)^x=e^(xInsinx) 再用复合函数求导方式算.这样就做得来了吧.

纪贞泡3288tanx的x次方+x的sinx次方 求dy/dx -
窦苏钥17196078040 ______ y = (tan x)^x + x^(sin x) = e^[xln tan x] + e^[sin x ln x] dy/dx = (tan x)^x [ln tan x + x cot x sec^2 x] + x^(sin x) [cos x ln x + (1/x) sin x] 思路:换成e为底后,再求导.

纪贞泡3288tanx+sinx<0求解集 -
窦苏钥17196078040 ______ 解:tanx+sinx<0 sinx/cosx +sinx<0 sinx(cosx+1)/cosx<0(cosx+1)tanx<0-1≤cosx≤1,0≤cosx+1≤2,要不等式成立,只需:tanx<0 kπ+π/2<x<kπ+π,(k∈Z) 不等式的解集为(kπ+π/2,kπ+π),(k∈Z)

纪贞泡3288lim x趋向于0 分母为tan3x 分子为sin4x -
窦苏钥17196078040 ______ 解:x趋向于0 则分母tan3x≈3x 分子sin4x ≈4x. 所以:tan3x/sin4x=3x/4x=3/4.

纪贞泡3288tanx+sinx=1 有一道题tanx+sinx=1 求x -
窦苏钥17196078040 ______[答案] tanx+sinx=sinx/cosx +sinx=1(sinx+sinxcosx)/cosx =1sinx+sinxcosx=cosxsinxcosx=cosx-sinx=√2cos(π/4 +x)1/2 sin2x =√2cos(π/4 +x)sin2x =2√2cos(π/4 +x)两边平方 sin²2x =8cos²(π/4 +x...

纪贞泡3288已知tanx+sinx=a,tanx - sinx=b,求证(a^2 - b^2)^2=16ab. (具体) -
窦苏钥17196078040 ______ 已知tanx+sinx=a,tanx-sinx=b, (a^2-b^2)=(a+b)(a-b)=(2tanx)*(2sinx)=4tanx*sinx,(a^2-b^2)^2=16(tanx)^2*(sinx)^2,16ab=16(tanx+sinx)(tanx-sinx)=16(tanx)^2*(sinx)^2.左边=右边,得证!