Question

代数式找规律,怎么推导出来的,如1,3,5,7,9.n

Answer 1

3-1=2,5-3=2,7-5=2……An-An-1=2

3-1+5-3+7-5+……An-An-1=2*(n-1)

An=2*(n-1)+1=2n+1