It is referring to the male chromosome whereas the the female gender chromosome is XX.
If you mean: xy2/xy then it can be simplified to y
XY is the male chromosomes, i dont know what the symbols for craziness are though
4
It means to have XY chromosomes, genetically.
xy - xy = 0
xy + xy = 2xy
If you mean, "x-3y = 12", then xy = 3y2 + 12y.
XY
X = 10 y is not a roman numeral
It is an expression in the form of: xy+7
The answer depends on whether xy are commutative numbers or operators in a permutation group.
The GCF is xy