1. (C) a statement in mathematics that shows that two amounts or totals are equal 等式，方程式
In the equation 2x+1=7, what is x? 在2x+1=7這個方程式中，x是多少？
Solve the equation 5x-3=27. 解答方程式5x-3=27。
2. (C, usually singular) the set of different facts, ideas, or people that all affect a situation and must be considered together （涉及平衡的）影響因素，綜合體
The tourist industry forms a crucial part of the region's economic equation. 旅遊業成了該地區經濟總量中一個至關重要的部分。
The question of cost has now entered the equation. 成本問題現已成為了影響因素。
When children enter the equation, further tensions may arise within a marriage. 有了孩子以後，緊張的情況可能增加，影響婚姻中的平衡關係。
3. (U, sing.) when you consider that two things are similar or connected （兩事物的）相似，聯繫
the equation of violence with power 暴力與權力之間的聯繫。
The equation of wealth with happiness can be dangerous. 把財富與幸福等同起來可能是危險的。