摘要: $$1 + x^2 + x^3 + ... = \frac{1}{1 x}$$ $$1 + (kx)^2 + (kx)^3 + ... = \frac{1}{1 kx}$$ $$1 + x^2 + x^3 + ... + x^n = \frac{1 x^{n + 1}}{1 x}$$ $$\sum_ 阅读全文
posted @ 2019-09-06 16:19 AlphaWA 阅读(155) 评论(0) 推荐(0) 编辑