2+4+6+8+...+(2n+4)=?

运用等差数列的知识来解答,要过程!!!
2025-12-18 02:47:18
推荐回答(1个)
回答1:

=2(1+2+3+4+....+n+2)
=2(1+n+2)(n+2)/2
=(1+n+2)(n+2)