
Integrals on TI85
I am learning about integrals right now but my book only gave me a short paragraph about the calculator saying "On a TI use the Is> command". I look through the calculator and find that command but don't know what to input after it. Sadly, I don't know where my manual is. (Crying) Anyone know what I should do?
Also, if anyone has the cheat codes for the TI85 that would be helpful. I could use infinite ammo.

Go here to download the guidebook.

On the TI85 (which is the same great calculator I have  I still think it's the best one TI has ever put out, with the possible exception of the TI86), you'd do 2nd  CALC  fnInt  function  ,  variable name  ,  lower limit  ,  upper limit  )  ENTER.
You want to see this, for example:
fnInt(x^2,x,0,1), then press ENTER. The result is
.333333333333
Does that help?

Yes that helps a lot thank you.
I'm still new to integrals, though, so do the "lower limit" and the "upper limit" mean how far to the left and right it extends, respectively?

Right. The TI85's fnInt(x^2,x,0,1) notation is numerically equivalent to
$\displaystyle \displaystyle{\int_{0}^{1}x^{2}\,dx.}$

Is there a way to specify for n? It keeps assuming $\displaystyle \displaystyle{\lim _{n \to \infty }$.

To what are you referring? Are you trying to do a trapezoidal or Simpson's Rule, without letting the number of partitions go to infinity? fnInt is going to try to compute an accurate numerical integral of your function. If you want to do a finite Riemanntype sum, use the sum seq command:
2nd  MATH  MISC  sum  seq  etc. (look this up in the manual for the exact syntax).
Is that what you're after?


No problem. Have a good one!