Bài 1:
a) B=24(52+1)(54+1)(58+1)(516+1)=(5-1)(5+1)(52+1)(54+1)(58+1)(516+1)
=(52-1)(52+1)(54+1)(58+1)(516+1)=(54-1)(54+1)(58+1)(516+1)
=(58-1)(58+1)(516+1)=(516-1)(516+1)=532-1<532=A
Vậy A>B.
Bài 1:
b) a+b+c=0 ⇔ (a+b+c)2=0 ⇔a2+b2+c2+2(ab+bc+ca)=0 mà ab+bc+ca=0
=>a2+b2+c2=0 ⇔ a2+b2+c2-ab-bc-ca=0 ⇔ 2a2+2b2+2c2-2ab-2bc-2ca=0
⇔(a-b)2+(b-c)2+(c-a)2=0 ⇔a=b=c=0.
* M=(a-1)2013+b2014+(c+1)2015=-1+1+1=1.
c) C=(x+2)(x+4)(x+6)(x+8)+2030=(x2+10x+16)(x2+10x+24)+2030
* Đặt t=(x2+10x+21) thì C=(t-5)(t+3)+2030=t2-2t-15+2030=t(t-2)+2015
=(x2+10x+21)(x2+10x+19)+2015.
Vậy C chia cho x2+10x+21 dư 2015.
