I'm not sure if this is particularly important, but so far through my studies I've only encountered DE with two related variables (e.g. ## \frac {dy}{dx} = 3x##).(adsbygoogle = window.adsbygoogle || []).push({});

Now, given another function with an additional variable that is UNRELATED to the two other variables, can this still be considered a differential equation (e.g. ## \frac {dy}{dx} = 3x + z## where z is a random variable)? Does this not meet it's definition?

If I'm not mistaken, all the variables have to be related and it is possible to have DE with infinite variables, as long as they are all related. Is my understanding wrong?

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# Definitions regarding DE

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