I use MathPad to scribble my equations. A slight problem is the automatic scale-function, which makes the screenshots all different in size. An example. I nicked it from some math site I forgot to save the address of. Sorry.
Say you want to solve this equation for x=3.
That will lead to zero divided by zero. Not good. Let's take another approach. If we added a little bit to 3, say ⌂x, which is really small, the two factors wouldn't be zero. Let's see what happens if we substitute that for x:
Now we can solve it.
With this solution, we calculate the limit for ⌂x to zero.
And we have our solution.
But what about another approach? As one of my physics teacher once told us, using math we didn't command at that time, "trick!".
And let's see what it brings us.
That's not weird, of course, it's l'Hopital's rule. For 0/0 and ∞/∞
Okay, classes are over. You can see that I scaled them all down to the same width (400 pixels wide). But as the program fills up that space and the equation gets shorter the font enlarges. I have found no way to scale the font to a predefined size.
addition July 9, 2015
I found MoboMath, €2,99, in the App Store and it seems to be able to handle it. It also includes LaTex and Wolfram Alpha integration and such.