VCAA 2009 Exam 2 Very Last Question

[Wingtips]

Hey guys,
I keep on running into problems with this question on my calculator (ti-89 titatinum). I put in everything exactly like in the solutions and t pops out to be -3.1 not 245. Im so confused.
Could someone please help?
Cheers

[Biceps]

Find the time needed for object to hit see bed, multiply this time by the speed since it's constant, then using pythagoras theorem find the distance to the object

[Wingtips]

Yep, I understand that but the time i get when i put the right equation in the calculator is -3.1 and not the required 245. Even though vcaa says thats the answer I should be getting

[Biceps]

maybe it's a fault with your calculator. Try use another one for tomorrows exam just in case.

[Wingtips]

It worked fine for everything else just that question. Could someone tell me how to fix it or if they ran into the same problem? Freaking out.

[Wingtips]

Anyone please?
If I put in a limit like T>0, all I get is (T-245.398)e^(2T)=-0.5
The answer is there but it's not explicitally saying T=245.398.
There's also the warning, 'more solutions may exist' but it only pops out -3.1.

[lnaa19]

It's not just you, I use the Ti-89 too and got -3.1 as well. I don't know why that is, but I ended up having to substitute high values again and again in order to get the answer.

[Wingtips]

Glad it wasn't just my calc! Thanks heaps.

I had a go at the app numerical solver, and if you plug in the equation and change the lower bound to 0, it gives the right answer. Never used it before but seemed to work. Thought it might help you too