@zareen said in MTH405 Assignment 1 Solution and Discussion: Show that the operation which is defined by is NOT a binary operation on N. Q. 1 Solution: When x + y is less than xy, then x + y - xy does not belong to N. So it is not a binary operation on N. Show that the set fbafc6b9-c88d-49e2-8d4c-bf3d558f731c-image.png is a group under the binary operation of multiplication. Q. 2 Solution: Hence G ={1,-1} is a group , since all the axioms of the group are satisfied on G={1,-1} with respect to binary operation multiplication.