- #1

xortan

- 78

- 1

## Homework Statement

e^(4x-5)=9e^(x+5)

## Homework Equations

log rules

## The Attempt at a Solution

I have tried this one a few times using slightly different methods and getting 2 answers and neither of them seem to be working when i plug them back into the equation.

Here is my first method...

1. Divide out the e^(x+5) so i get e^(4x-5)/e^(x+5) = 9

2. Take the natural log of everything so i end up with

(4x-5)lne/(x+5)lne = ln 9

3. After doing the algebra i got the answer to be 8.87 (rounded to 3 sig figs), but it wasnt checking out when i plugged it back into the equation

Here is my second method...

1. I just started going crazy with the natural logs getting

(4x-5)lne - (x+5) ln 9e

The ln9e don't quite sit right with me tho, however after doing the algebra i get x=-10, this doesn't seem to check out either...please help!

## Homework Statement

(3^7x)(27^x)=9

## Homework Equations

logs

## The Attempt at a Solution

Alright well since i know that they are all powers of 3 i changed the bases so the equation became

(3^7x)((3^3)x)=3^2

Then i just looked at the exponents and ended up with

21x^2 = 2

Did the algebra and this one isn't working in the orignal equation either >.<

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