英语周报2023到2023第四期答案

英语周报2023到2023第四期答案已经整理完毕，供同学们学习参考，更多英语周报答案，请关注本站。

去b,然后转化成关于e的方程(或不等式)求解12.ACD考查目标本题考查导数的应用,函数的零点,考查转化与化归思想,运算求解能力、推理论证能力思路点拨令fx)=0,=°,则1>0,x=hmt,故f(x)=0转化成血1-1)=02h1=(-1)=0今(0=-m=(-)然g(1)=0.问题转化成函数g(t)在(0,+∞)上只有一个零点1.8()=1(+)令h(t)=-a2+t-a,h(t)图象为一条抛物线,开口向下,对称轴=n>0,过点(0,-a),A=1-4a2.当△≤0,即1-4a2<0,a≥5时,g()≤0,g(n)在(0.+∞)上单调递减,g(1)=0,此时符合题意;当△>0,即1-4a2>0,0 0,对称轴=20>1,所以0<4<1 <与,则b(1)在(0,)上单调递2)上单调递增,(2,+=)上单调递减由于g(1)=0,所以g(2)> 0.取,又与1+与=,所以2< 2,则F(b)=2b-e2-e<2b-e2<0,所以F(b)在(2,+=)上单调递减,又F(2)=4-2-e-2<0,所以g(a)<0,g(t0)<0,结合零点存在性定理可知,函数g(1)在(t2,)上存在一个零点,不符合题意,故实数a的取值范[2…=)故速A,D

参者范文Dear PaulThe craze for winter sports is on the rise in China. I,'m writing tocommend skating to youFirst, skating can help build up your body. It can also removestress and tension and keep you relaxed, which contributes to yourphysical and mental health. Besides, your sense of balance andfiexibility will get improvedYoud better choose a professional coach and a safe stadium.Takecare of yourself while exercising. After all safety always comes firstHope you can enjoy it.YoursLi Hua

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