If the Ax and Ay, some are positive and some are negative, this is the way by which we have learned we should combine multiples of i.

如果 Ax 和 Ay 有正有负,这就要用到我们所学过的方法,将所有 i 的倍数加起来

耶鲁公开课 - 基础物理课程节选

A very important result is that if two vectors are equal, if A = B, the only way it can happen is if separately Ax is equal to Bx and Ay is equal to By.

这里有一个相当重要的结论,如果两个矢量相等,例如 A = B,那么当且仅当,Ax = Bx 和 Ay = By 分别成立

耶鲁公开课 - 基础物理课程节选