SOLUTION: Last problem I'm having issues with is e^(12-5x)-7=123 I got as far as adding 7 to both sides and got stuck

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Last problem I'm having issues with is e^(12-5x)-7=123 I got as far as adding 7 to both sides and got stuck      Log On


   

Question 1042051: Last problem I'm having issues with is
e^(12-5x)-7=123
I got as far as adding 7 to both sides and got stuck
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!

e%5E%2812-5x%29-7=123

e%5E%2812-5x%29=130

Learn to write exponential equations as logarithm equations:

B%5EC=A and C=log%28B%2CA%29 are equivalent.

So e%5E%2812-5x%29=130 is equivalent to 

12-5x=log%28e%2C%28130%29%29

An abbreviation for loge is ln, so

12-5x=ln%28130%29



x+=+-ln%28130%29%2F5%2B12%2F5

Get your calculator:

x+=+1.42649311

Edwin