(iii)

(3)/(4)N=2\\\\pi k=>

There is no

N

such that

(3)/(4)N=2\\\\pi k

, so

x[n]

is not periodic.\ (b) For discrete-time signals, if

\\\\Omega _(x)=\\\\Omega _(y)+2\\\\pi k

and

\\\\Omega _(x)\\\\tau _(x)+\\\\theta _(x)=\\\\Omega _(y)\\\\tau _(y)+\\\\theta _(y)+2\\\\pi k

, then

x[n]=y[n]

.\ (i)

,(\\\\pi )/(3)!=(8\\\\pi )/(3)+2\\\\pi k

(the closest is

k=-1

), so

x[n]!=y[n]

\ (ii)

\\\\Omega _(x)=\\\\Omega _(y),(3\\\\pi )/(4)(2)+(\\\\pi )/(4)=(3\\\\pi )/(4)-\\\\pi +2\\\\pi k,k=1

, so

x[n]=y[n]

\ (iii)

\\\\Omega _(x)=\\\\Omega _(y),(3)/(4)(1)+(1)/(4)=(3)/(4)(0)+1+2\\\\pi k,k=0,x[n]=y[n]