[toán 11] bt @@

N

newstarinsky

3) ĐK $sin2x>0$
PT trở thành
$sin^22x+cos^42x-1=0\\
\Leftrightarrow cos^42x-cos^22x=0\\
\Leftrightarrow cos^22x.sin^22x=0$

1)PT trở thành
$\dfrac{\sqrt{2}|sinx|}{sinx}=\sqrt{2}(cosx-\dfrac{1}{2})$
Xét 2 TH nhé

 
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