Đáp án:
$A\,\vdots\,8\,\forall\,n\in \mathbb{N}$,n lẻ.
Giải thích các bước giải:
$A=n^2+4n+3$
$A=n^2+n+3n+3$
$A=n(n+1)+3(n+1)$
$A=(n+1)(n+3)$
Vì $n$ lẻ $=>n=2k+1(k\in\mathbb{N})$
$=>A=(2k+1+1)(2k+1+3)$
$=>A=(2k+2)(2k+4)$
$=>A=4(k+1)(k+2)$
Vì $(k+1)(k+2)$ là tích 2 số nguyên liên tiếp
$=>(k+1)(k+2)\,\vdots\,2$
$=>4(k+1)(k+2)\,\vdots8\,$
$=>A\,\vdots\,8\,\forall\,n\in \mathbb{N}$,n lẻ.
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calli : Spanking NL : I like spank . How about you Trả lời nghị luật
Giải giúp mình bài 1 với bài 2 đi ạ
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10,539 - 2,1347= 19,8-17,5= 17,3 x 8,6 = 3,4 x 6,7
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