1.6.35 Fields, Groups, Rings

Condition: Find out, a ring or field is an algebraic system \ ((U, \ Bigoplus, \ Otimes) \), where \ (U = \ Left \ {\ LEFT (\ Begin {Array} {ll} A & 0 \\ 0 & 0 & 0 & 0 & 0 & 0 & b \ end {array} \ right) \ mid a, b \ in r \ right \}, \ bigoplus \)-the addition of matrices, \ (\ otimes \)-multiplication of matrices.