x as a function of time, and when you have the correct solution x and you substitute that back into that differential equation, that equation will have to be satisfied.
根据时间的变化，x，is，，of，course，，changing，in，some，way,发生相应的变化，当你得到了,和时间的正确关系，for，x，as，a，function，of，time,你把它代入,这个微分方程，这个等式，就能得到满足。