1) $A=(2x+3y)-2.(2x-y)^2$
$ = 2x+3y-2.(4x^2-4xy+y^2)$
$ = 2x+3y-8x^2+8xy-2y^2$
2) $M = 3.(2^2+1).(2^4+1).(2^8+1).(2^{16}+1)$
$ = (2^2-1).(2^2+1).(2^4+1).(2^8+1).(2^{16}+1)$
$ = (2^4-1).(2^4+1).(2^8+1).(2^{16}+1)$
$ = (2^8-1).(2^8+1).(2^{16}+1) = (2^{16}-1).(2^{16}+1) = 2^{32} - 1< 2^{32}$
Vậy $M<2^{32}$