英语翻译2,-4,-8.In the sequence above,each term after the second is equal to the product of the 2 preceding terms.For example,the third term,-8,is the product of 2 and -4.How many of the first 100 terms of this sequence are negative?

英语翻译2,-4,-8.In the sequence above,each term after the second is equal to the product of the 2 preceding terms.For example,the third term,-8,is the product of 2 and -4.How many of the first 100 terms of this sequence are negative?
英语翻译
2,-4,-8.
In the sequence above,each term after the second is equal to the product of the 2 preceding terms.For example,the third term,-8,is the product of 2 and -4.How many of the first 100 terms of this sequence are negative?

英语翻译2,-4,-8.In the sequence above,each term after the second is equal to the product of the 2 preceding terms.For example,the third term,-8,is the product of 2 and -4.How many of the first 100 terms of this sequence are negative?
解你说的那道题：
一个口袋中有6个薄片,号码为1到6,如果随机选择2个薄片,不能更换,并且让薄片上的值相乘,乘积将大于20的概率是多少?
乘积大于20：4x6,5x6.所以有四种排列：4和6,5和6,6和4,6和5.
六取二排列数：6 P 2 = 6!/4!= 30
取30种排列其中的4种：概率为4/30 = 2/15