观察下面三行数:2,-4,8,-16,32,-64,...;① 4,-2,10,-14,34,-62...;②观察下面三行数:①2,-4,8,-16,32,-64,...; ② 4,-2,10,-14,34,-62...③1,-2,4,-8,16,-32,...写出每行第五十个数要有列式
问题描述:
观察下面三行数:2,-4,8,-16,32,-64,...;① 4,-2,10,-14,34,-62...;②
观察下面三行数:①2,-4,8,-16,32,-64,...;
② 4,-2,10,-14,34,-62...
③1,-2,4,-8,16,-32,...
写出每行第五十个数
要有列式
答
1 [ (-1)^(n+1)] 2^n
2.
3 [ (-1)^(n-1)] 2^(n-1)
前面的控制符号,后边的控制数的变化