2022英语周报第3489期答案

解:(1)当a=-1时,f(x)=|3x 11-2由|3x 1|-2≤5,整理得-7≤3x 1≤7解得一3≤r≤,因此不等式()≤5的解集为(x-3≤x≤2)(2)当x∈R时,f(x) 3g(x)=|3x-a| 2a |3x-3≥|3x-a-3x 3| 2a=|3当x=1时等号成立,所以当x∈R时,f(x) 3g(x)≥9等价于|3-a 2a≥9.①当a≤3时,①等价于a 3≥9,无解当a>3时,①等价于a-3 2a≥9,解得a≥42467890所以a的取值范围是[4, ∞)评分细则(1)第一问中,在求不等式∫(x)≤5的解集时,去掉绝对值得2分,第一问全部正确得4(2)第二问中,写出∫(x)十3g(x)的最小值得2分,后续步骤每讨论一种情况各得2分.

第四部分写作第一节短文改错Last Friday, we had a PE lesson on theplayground, during that we learned how to do thehichlong jump. After some warming-up exercises, ourexerciseteacher showed us how to do it and asked us to payattentionA safety. Then we followed the teacher andpractised one after other. When it was my turn, Ianotherfeel very nervous. I failed at my first try, and I didn'tbutlose heart. I kept on practise. At last, I jumpedactIsover 2 metres longer. I was exciting that I succeededlong已xThis lesson made me realize that it's true that hardwork will eventually pay A off

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