zxx020424:17.(1)2n (2)n²+n+1/3×1/4的n次方+1/3回到原帖
ZY010829:你姐肯定有办法回到原帖
ZY010829:我还以为你直接发过程哩回到原帖
zxx020424:18(1)连接a1c1交b1d1于点m,连接?om然后证明a1ocm为平行四边形,然后后面。。。回到原帖
zxx020424:打这个字打的心累回到原帖
zxx020424:我去做了,一会儿发回到原帖