Vuthuydung551idn
Answered

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Giải phương trình:
Sin^4 x - cos^4 x =1/2

Sagot :

Atrisafalidn

Step-by-step explanation:

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Caylusidn

Hello,

[tex]cos^4(x)=(cos^2(x))^2=(1-sin^2(x))^2=1+sin^4(x)-2*sin^2(x)\\\\sin^4(x)-(1+sin^4(x)-2sin^2(x))=\dfrac{1}{2} \\\\1-2sin^2(x)=\dfrac{1}{2} \\\\\\sin^2(x)=\dfrac{1}{4} \\\\sin(x)=\dfrac{1}{2} \ or\ sin(x)=-\dfrac{1}{2} \\\\\\modulo\ 2\pi: \\\\x=\dfrac{\pi}{6}\ or\ x=\dfrac{5*\pi}{6}\ or\ x=-\dfrac{\pi}{6}\ or\ x=-\dfrac{5*\pi}{6}[/tex]

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