13.求下列各函数在指定点z0处的泰勒展开式,并确定它们的收敛半径:-|||-(1) dfrac (z-1)(z+1), _(0)=1;-|||-(2) dfrac (z)((z+1)(z+2)) ,z0=2;-|||-(3) dfrac (1)({a)^2} ,_(0)=-1;-|||-(4) dfrac (1)(4-3z), _(0)=1+i;-|||-(5)tanz, _(0)=dfrac (pi )(4);-|||-(6)arctan z, _(0)=0.