Ответ:

[tex]3[/tex]

Объяснение:

[tex]x^5-5x=x(x^4-5)=[/tex]

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[tex]x^2-x-1=0\\\\x^2=x+1\ \ \ |()^2\\\\x^4=x^2+2x+1[/tex]

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[tex]=x(x^2+2x+1-5)=x(x^2+2x-4)=x(x^2-1+2x-3)=[/tex]

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[tex]x^2-x-1=0\\\\x^2-1=x[/tex]

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[tex]=x(x+2x-3)=x(3x-3)=3x(x-1)=[/tex]

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[tex]x^2-x-1=0\\\\x^2-x=1\\\\x(x-1)=1[/tex]

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[tex]=3\cdot 1=3[/tex]