Re: [中學] 資優數學兩題
※ 引述《Intercome (今天的我小帥)》之銘言:
: 1. 已知D是三角形ABC內一點,E是AC的中點。若AB=6,BC=10,
: 且角BAD=角BCD,角EDC=角ABD。求DE = ?
: 2. 已知f(x)是定義在實數上的函數,f(0)=2,對任意實數x,滿足
: f(5+2x) = f(-5-4x),f(3x-2)=f(5-6x)。求f(106) = ?
5+2x=y --> -5-4x = 5-2y
f(5+2x) = f(-5-4x) --> f(x)=f(5-2x) --> f(x) = f[(5-x)/2]
f(3x-2) = f(5-6x) --> f(x)=f(1-2x) --> f(x) = f[(1-x)/2]
f[(1-x)/2] = f[(5-x)/2] -->f(x)=f(x-2)
f(106)=f(104)=...=f(0)=2
: 以上兩題再請版上高手能夠提供想法,謝謝!
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※ 編輯: Tiderus (123.240.102.135), 01/23/2017 20:37:35
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※ 編輯: Tiderus (123.240.102.135), 01/25/2017 15:25:20
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