Question

数学问题，最好把答案写在纸上，照相上来，谢谢

Answer 1

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把x2用y表吵谨配示
x1用x表示
并假设y>x
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[f(y)-f(x)]/(y-x)
=[(2lny-2y+2)-(2lnx-2x+2)]/(y-x)
=2*[ln(y/x)-(y-x)]/(y-x)
=2*[ln(y/x)/(y-x)-1]
=2[ln(1+(y-x)/x)/(y-x)-1]
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根据升指ln(1+x)<x,当x>0.
可得ln(1+(y-x)/x)<(y-x)/x
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所晌首以
=2[ln(1+(y-x)/x)/(y-x)-1]
<2[((y-x)/x)/(y-x)-1]
=2(1/x-1)