1. the interior angel of a hexagon form an arithmetic sequence. find the sum of the smallest angle and the largest angle.
A. 180
B. 220
C. 240
D. 360
要步驟謝謝,答案是240,忘記了怎樣計。
2.
1+2+2^2+2^3+...+2^=?
A. 2^n-1
B. 2^(n+1)-1
C.(2^n-1)/2
D.(2^(n+1)-1)/2
我認為答案是B,但是SOLUTION係C.到底是我錯還是SOL印錯?