1. Rút gọn biểu thức: A= (2x+3y) – 2(2x-y) ²
2. Cho M= 3( 2 ² +1).[(2^4) +1].[(2^8)+1].[(2^16)+1]
So sánh M với 2^32
1. Rút gọn biểu thức: A= (2x+3y) – 2(2x-y) ²
2. Cho M= 3( 2 ² +1).[(2^4) +1].[(2^8)+1].[(2^16)+1]
So sánh M với 2^32
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 $M<2^{32}$