[Toán 8]Chứng minh đẳng thức

L

lp_qt

$a^8-b^8=(a^4+b^4)(a^4-b^4)=(a^4+b^4)(a^2+b^2)(a^2-b^2)$
$=(a^4+b^4)(a^2+b^2).[(b+1)^2-b^2]=(2b+1).(a^4+b^4)(a^2+b^2)$
$=(a+b).(a^4+b^4)(a^2+b^2)$

\Rightarrow đpcm
 
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