21.for (xy) er,consider the series lim 2,k=0 then the series n-ot,k=0 converges for (x, y) in. (a)-1.1)(0) (b) rx(-1,1) menatics net dec. 2015) (c (-1,1)x(-11)

21.For (xy) eR,consider the series lim 2,k=0 Then the series n-ot,k=0 converges for (x, y) in. (a)-1.1)(0) (b) Rx(-1,1) Menatics Net Dec. 2015) (c (-1,1)x(-11) (d) RxR natics c. u.