Thread: can't solve exponential

I am trying to draw x=3e^4t+12e^-t where t is x axis and x is y axis

I don't understand how from visualising this i can tell it is a growing function and doesntcross the t axis. I drew for instance y = -2e^4t +12e^-t since I knew it would cross the t axis as I could put y=0 and solve it.

Putting x=o however apparantly cannot be solved. Where am I going wrong,

0 = 3e^4t + 12e^-t
-e^4t = 4e^-t
e^4t = -4e^-t
lne^4t = -ln4 + lne^-t
4t = -ln4 -t
t = -(ln4)/5

Originally Posted by i_zz_y_ill

e^4t = -4e^-t
lne^4t = -ln4 + lne^-t

Wrong!



But actually there is no real number called

What really should have been done was since



Thus