Question

PLEASE HELP!!
solve the equation
(e^x-81e^-x)/2 =9

which is the solution in terms of natural logarithms?
x=__________
OR
there is no solution

what is the decimal approximation for the solution?
x=______________
OR
There is no solution

Answer 1

where is the eqation?

Answer 2

the equation is on the top

Answer 3

I've simplified this equation to e^2x-18e^x-81=0
You understood how to?

Answer 4

yes

Answer 5

e^x=t

t^2-18t-81=0
you are aware with ax^2+bx+c=0 and how to find it's roots. Right?

Answer 6

yes

Answer 7

well you will get two values of 2, which will be values of e^x.
Then take the log on both sides, you'll get x.

Answer 8

so do I use the quadratic formal to solve the equation?

Answer 9

Yes.

Answer 10

Quadratic for the value of e^x. and then logarithm to obtain x.

Answer 11

I got \[\frac{ 18\pm \sqrt{648} }{ -36 }\]

Answer 12

is that right? how do you logarithm it?

Answer 13

@NeetziD