the question is as follows:
For all numbers x and y, let the operation ■ be defined by x ■ y = xy-y. If a and b are positive integers, which of the following can be equal to zero?
does one distribute choices II and III to a■b + b■b and a■a + a■b respectively? How does that help?
There is just something about the use of symbols that has not registered yet. Thanks.