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https://blog.mlchen.org/102/%e5%be%ae%e7%a9%8d%e5%88%86%e8%a6%81%e9%81%8e%e5%b0%b1%e8%a6%81%e9%9d%a0%e5%a5%b9%e4%ba%86
微積分要過就要靠她了!