已知函数F(X)=X的平方-2ax+5(a>1) 若F(X)的定义域和值域都是【1,a】,求实数a的值
人气:373 ℃ 时间:2019-08-20 14:21:25
解答
x^2-2ax+5=0对称轴为x=a,
又a>1,所以x=a时F(X)有最小值1,即a^2-2a*a+5=1①
x=1时F(X)有最大值a,即1-2a+5=a②
①②联合解得a=2
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