等差數列求和 | Summation of an Arithmetic Sequence
影片內容：
00:05 – 數列的和 | summation of a sequence
02:17 – 等差數列求和公式 | derivation of the summation formula of arithmetic sequence
09:03 – 例子 1 | example 1
10:53 – 例子 2 | example 2
14:05 – 例子 3 | example 3
00:05 – 數列的和 | summation of a sequence
02:17 – 等差數列求和公式 | derivation of the summation formula of arithmetic sequence
09:03 – 例子 1 | example 1
10:53 – 例子 2 | example 2
14:05 – 例子 3 | example 3