[单选题]已知x(n)是实序列,x(n)的4点DFT为X(k)=[1,-j,-1,j],则X(4-k)为()。A . [1,-j,-1,j]B . [1,j,-1,-j]C . [j,-1,-j,1]D . [-1,j,1,-j]
设数列x_{n)}满足:x_(1)>0,x_(n)e^x_(n+1)=e^x_(n)-1(n=1,2,...).证明x_{n)}收敛,并求极限lim x_(n)
[名词解释] 辛弃疾Xīn Qì jí
18.设f(x)=lim_(ntoinfty)(x)/(n)(e^-(x^(2)/(n^2))+e^-(x^(2)/(n^2))+...+e^-x^(2)),求
11.设在可测集E上, _(n)(x)Longrightarrow f(x), 而对任意正整数n和a.e.的 in E, _(n)(x)=(f)_(n)(x),
微分方程^(n)=(e)^ax+(x)^b的通解为( )^(n)=(e)^ax+(x)^b^(n)=(e)^ax+(x)^b^(n)=(e)^ax+(x)^b^
设数列x_{n)}由x_(1)in(-infty,+infty)和x_(n+1)=(1)/(3)x_(n)+(2)/(3)-(1)/(2)int_(1)^x_(
∫f(x^n)x^(n-1)dx=F(x^n)+C(C ∫f(lnax)1/xdx=F(lnax)+C.(a≠0)(D.) ∫f(e^(-x))e^(-x)dx