英语周报 JJY 2018-2答案

參考范文about a week later, Pomilla and Andrew got to meet her son'sSavion comilla and Andrew arrived at the metro station at theappointed time, anxiously waiting for Case to come. When Casearrived with a big smile, they felt very happy and excited. Casehugged Andrew warm-heartedly and reached out his right hand, sayingto him. Would you like to take it again?"without hesitation theboy took it and held it firmly. After talking for some time, Pomillatook out the badge and gave it back to Case. Many passengers tookictures of the sceneTaylor Pomilla was moved and expressed her thanks to Caseagain She asked Case how he could calm andrew down at that timeCase told her that he had a daughter with autism and that he hadreceived special training on how to deal with autistic children. Hepromised to visit them often to help Andrew grow up happily. As hewas talking, he took out a police badge that he made by hiimself andgave it to Andrew, who was more than happy to accept it. Ever sincethen they have been friends

ex-laet21.【解析】(1)f(x)=xae(x-1) 1-x(x-1)(ae-1)①当a≤0时,ae-1<0,由f(x)>0→0 1f(x)在(0,1)上递增,在(1, ∞)上递减②当0 1,由f(x)>00 ln由f(x)<0→1 0恒成立,f(x)在(0, ∞)上递增④当- 0→0 1,由f(x)<0→ln- 0→x>1,由f(x)<0→0 0.g(x)单调递增,当x∈(xn ∞)时,g(x)<0g(x)单调递减g(x)sg(ro)=七-hnx e-1=1-lx e-2因为g(x0)在[一,1上递减,∴g(x)≤g()=a na e-2只要证:ae-l≥a lna e-2令F(a)=ae-1-a-lna-e 2,则F(a)=e-l、>0所以函数F(a)在a∈[, ∞)上递增,∴F(a)≥F(1)=e-1-1-0-e 2=0成立所以原命题成立

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