Why isn't it mathematically rigorous to treat dx's and dy's as variables?
3360
Is $\frac{\textrm{d}y}{\textrm{d}x}$ not a ratio?
31273
What does $dx$ mean?
35671
Why can a discontinuous function not be differentiable?
127964
Confused about the possibility of different differentiable structures.
43667
Is $f(x,y(x))$ a function of two variables? If so, how is that possible?
973
Is the property "being a derivative" preserved under multiplication and composition?
152157
Math with interpolated variables?
157748
Why should the equality of mixed partials be "intuitively obvious"?
90325
Why use the derivative and not the symmetric derivative?
20280
Proving that expression is equivalent to the definition of derivative
36574
Does separation of variables in PDEs give a general solution?
30781
Why the representation in the form of $Z'X(X'X)^{-1}X'Z$ can not be simplified into $Z'Z$
153158
how to get $dx\; dy=r\;dr\;d\theta$
86407
Why is it differential equations exist on an interval instead of a domain?
46010
Why don't we define division by zero as an arbritrary constant such as $j$?
115712
Application of Derivatives rigorous proof
77464
Prove that ${x dy - y d x\over x^2 + y^2}$ is not exact