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问题: 数学:函数求值

f(x)=loga(x),(a>0,且a≠1).若f(x1x2…x2005)=8,
那么f(x1^2)+f(x2^2)+…+f(x2005^2)=?

解答:

f(x1x2…x2005)
=loga(x1x2…x2005)
=loga(x1)+loga(x2)+…+loga(x2005)
=8
又f(x^2)=loga(x^2)=2loga(x)
所以
f(x1^2)+f(x2^2)+…+f(x2005^2)
=2[loga(x1)+loga(x2)+…+loga(x2005)]
=16