[Math] What could be the easiest way to remember all common derivative and common integral formulas

calculus

Remembering the following formulas has been a nuisance for me for years now.

Common Derivatives

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Common Integrals

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  1. They are too many in numbers
  2. Intuition doesn't work
  3. I mix up derivatives and integrals frequently

Can anyone suggest the best way to remember them?

Best Answer

Memorize the derivatives of $x^n$, $e^x$, $\ln|x|$, $\sin x$, $\cos x$, $\arcsin x$, $\arctan x$, and maybe $\tan x$ (which are used all the time), and derive the rest whenever you need them (which isn't often, in my experience).

Then many of the integrals will just be “backwards versions” of what you already know, so there's no extra memory required to store them, and for those that are not, you can compute them when needed rather than memorizing them. For example, $$ \int \ln x \, dx = \int 1 \cdot \ln x \, dx = \cdots \quad \text{(integrate by parts)} $$ or $$ \int \tan x \, dx = \int \frac{\sin x}{\cos x} \, dx = - \int \frac{-\sin x}{\cos x} \, dx = - \ln|\cos x| + C \qquad \text{(pattern recognition, $\tfrac{f'(x)}{f(x)}$)} . $$ One tricky case, which I would recommend memorizing (even though it's not included in your list) is $$ \int \frac{dx}{\sqrt{a^2+x^2}} = \ln\left|x + \sqrt{a^2+x^2}\right| + C . $$

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