The function D(h)=7e^-0.4(h) can be used to determine the milligrams D of a certain drug in a patient's bloodstream h hours after the drug has been given. How many milligrams will be present after 9 hours. Round three decimal places.

Question

so 7e^(-0.4 x 9) = .191

To get this answer I used a TI-83 calculator. My question is how do I enter this in a TI-30 calculator.? In my math class we are not allowed to use the TI-83.

Answer 1

I know for the simplest TI-30, they have an INV button and for later models they have a 2ND function button, but here is my suggestion

.4
±
x
9
=
INV or 2ND
ln
=
x
7

you should get .191266..

Answer 2

Thank You!