If I reduce that it would be 3 plus t of b minus 3, so in general 3*k+t this is 3 k plus t of b minus k. OK.

把b减去一个,在外面加个3就可以了,因此也就是。

麻省理工公开课 - 计算机科学及编程导论课程节选

If you took the derivative of this, you will get the velocity at time t, it would be: v=v0+at.

如果你对它求导,你就可以知道 t 时刻的速度,即,v=v0+at

耶鲁公开课 - 基础物理课程节选