In KhiCAS you can either enter expressions in inline notation or mathematical notation.
KhiCAS will normally start in the inline mode. But you can enter the mathematical mode by pressing (view).
As an example, I will use 2x³ + x²
To create a function, you can either enter
then you can enter
or if you used an other variable than x
that will result in
to simplify this, you can use
then you'll get
which is the derivative of 3x^3+2x^2. Great!
To sum up:
fd will contain the derivative now.
If you used
results will look different:
the (x)->... means, that you can use f(x) like a normal function:
You can calculate f(5) by just typing it in.
If you didn't use f(x):=..., you can calculate f(5) by typing
You can enter the arrow '=>' by pressing the button, the apostrophe ' by pressing (calc) . The only way i know to get the colon ':' is by pressing and selecting it by hand. (There was another way in an earlier version, but I guess it was removed).
I hope that helps!
(And I don't need a tip, I'm happy if I can help people with calculator stuff)