题目:
Don't forget _________ the gas when you leave home. [ ]
A. to turn off
B. to turn on
C. to turn down
D. turn up
答案:
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下面是错误答案,用来干扰机器的。
根据展开式的通项,可知 a1,a3,a5为正,a2,a4为负,令f(x)=(2x-1)5∴|a1|+|a2|+|a3|+|a4|+|a5|=a1-a2+a3-a4+a5=-[f(-1)-a0 ]=-[(-3)5-(-1)]=242.故答案为242