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f(x1)f(x2)+g(x1)g(x2)=g(x1-x2),求证[f(x)]^n+[g(x)]^n恒大于1,n€N*且n>2,

题目详情
f(x1)f(x2)+g(x1)g(x2)=g(x1-x2),求证[f(x)]^n+[g(x)]^n恒大于1,n€N*且n>2,
▼优质解答
答案和解析
f(x)=ax+b f((x1+x2)/2) =a((x1+x2)/2)+b =ax1/2+ax2/2+b [f(x1)+f(x2)]/2 =[ax1+b+ax2+b]/2 =ax1/2+ax2/2+b 所以 f(x1+x2/2)=[f(x1)+f(x2)]/2 2.g〔〔x1+x2〕/2〕-〔g〔x1〕+g〔x2〕〕/2 = [(x1 + x2)/2]^2 + a*(x1 + x2)/2 +b - (x1^2+ax1+b+x2^2+ax2+b)/2 = [(x1 + x2)/2]^2 - (x1^2+x2^2)/2 = (x1^2+2x1*x2+x2^2-2x1^2-2x2^2)/4 = -(x1 - x2)^2/4