X(e)=FTT k) -k) ∑cs(k'(w-x) 5.设如图所示的序列x(n)的FT用X(e")表示,不直接求出X(e"),完成下列运算: (1)X(e) (5)「x(e (1)X(e) ∑ (2)」x(eo)h=x(O)·2r=4 ieg a mpie:ClICOII (2)x2(n)==5(n+1)+5(n)+-(n-1) (3)x(n)=a"lu(m),0<a<1 x2(e~)=∑x(mle 1+-(e+e")=1+cosw xe")=∑au(n)em=∑aem 7.设 (1)x(n)是实偶函数