when inputing derivatives into a TI-89, what is correct format?

for example, the first derivative of

f(x)=9x^2

the method should be F3, #1

then: d(9x^2,x) correct?

each time i try, it tells me: "Non-algebraic variable in expression"

what am i leaving out here?

2/23/2006 4:35:56 PM

do you have x defined as a value? type 'x' and hit enter. if it's a value, you need to clear it

2/23/2006 4:39:06 PM

ah ha....that got it, thanks

2/23/2006 4:45:45 PM

np

2/24/2006 12:03:03 AM