Arabic to English Science Mathematics & Statistics calculus

From reading Arabic notes online, I understand the concept of دالة مقابلة to be a function with the same derivative as another function, which may then vary with a different constant of integration. However, I can't find a term to express this idea in English.

Note: I do not believe this is "equivalent function". That phrase is used in CS in English to mean functions that do the same thing. I haven't found examples in calculus contexts, but please let me know if you find any.

See screenshots below:

http://imgur.com/R7vXDg8

http://imgur.com/uwS4q4J

Thank you!