# Need help fast: Pre-Calculus Problem

• Apr 19th 2008, 12:16 AM
BostonBlaze
Need help fast: Pre-Calculus Problem
I have a TI-83 graphing calculator and I need to graph the following function:

s(t) = -16t^2 + 80t + 7

I have no idea how to graph this on the graphing calculator. Any help at all would be greatly appreciated
• Apr 19th 2008, 12:17 AM
Moo
Hello,

On the left and up side, you have a button "Y="
For graphing, "Graph"
• Apr 19th 2008, 12:25 AM
BostonBlaze
I'm sorry, I should have been a little more specific. I get to the point of entering the function and hitting graph, but it doesn't graph correctly. Do I enter the EXACT function or is it entered differently? Once you hit Y= what would you type?
• Apr 19th 2008, 12:29 AM
Moo
Oh yeah I see... You have to replace t by x, since the calculator asks for a function y1(x) :) (at least, it works this way on my TI-89)
• Apr 19th 2008, 12:36 AM
BostonBlaze
when I select Y= I enter the following: -16x^2 + 80x +7 then I hit graph. It's supposed to graph a half oval shap, but it graphs a straight line. Am I not enering the function correctly, even by substituting x with t?
• Apr 19th 2008, 12:45 AM
Moo
Perhaps it depends on the zoom/the window...
Or try to enter
Code:

`-16*x^2+80*x+7`
Actually, there are many possibilities, and these are the ones coming firstly for me :D
• Apr 19th 2008, 12:49 AM
BostonBlaze
It's still not working. I'm doing something wrong. Thank you so much for the help though. I really appreciate it
• Apr 19th 2008, 12:52 AM
Moo
Can you tell me what's in "window" ?

And are you sure you're in the right mode for graphing ? (there is parametric, polar, etc...)

Have you ever saved x as a constant ? I mean sometimes it occurs that in programs you need to give a value to x, and that it has kept it in memory...