三种一阶和二阶微分方程的解法（常系数、变系数）

https://www.bilibili.com/video/BV1zX4y1V7ce/?p=3&spm_id_from=pageDriver&vd_source=f911c2c08bf9fde8550390cc7145f5f3

 

 

 

https://www.bilibili.com/video/BV1nN411X7H5?spm_id_from=333.337.search-card.all.click&vd_source=bdbb5be671dc7bcfadbe64bf3d0d2f95