<PRE><B>Question 803858</B>
x^4-16 it says to plug in 1- the square root of 5 in my x spot.
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f(x) = x^4-16
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f(1-sqrt(5)) = (1-sqrt(5))^4 - 16
Note: That is a difference of squares.
Factor::
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= [(1-sqrt(5))^2-4)]*[(1-sqrt(5))^2)+4] 
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Square the squaring terms::
= [1+5-2sqrt(5)-4]*[1+5-2sqrt(5)+4]
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= [2-2sqrt(5)]*[10-2sqrt(5)]
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= [2(1-sqrt(5))]*[2(5-sqrt(5)]
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= 4(1-sqrt(5))(5-sqrt(5))
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= [4(5-6sqrt(5))+5]
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= 20-24sqrt(5) + 5
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= 25 - 24sqrt(5)
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Cheers,
Stan H.
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