[M2.2(Z); +, x] is an unitary ring b M22(z) a,b,c,d∈Z} ◆ Zero of ring(0)2×2, ◆ Identity of ring is 00 ≠ ≠U2×2 10Y00 (O),x2 zero-divisor of ring 0O八01[M2,2(Z);+,] is an unitary ring  Zero of ring (0)22 ,  Identity of ring is ( ) { | , , , } 2,2 a b c d Z c d a b M Z          =         1 1 ( )2 2 0 0 0 1 0          ( )2 2 0 0 1 0 0          ( ) 0 2 2 0 1 0 0 0 0 1 0  =                 zero - divisor of ring