Posted by Lee on Sunday, November 14, 2010 at 2:33am.
Problem: Use Common or Natural Logarithims to solve the exponential equations symboliclly.
2e^7x+4=4
(Round to four decimal places)
I tried solving this way
2e/2^7x+4=4/2
e^7x+4=2
ln e^7x+4=ln 2
7x+4=ln 2
7x+44=ln 24
7x=ln 24
7x/7=ln 24/7
x=ln 24/7
then I at a lose at this point.
What step should I perform next.
I know I'm suppose to use the calculator for the estimated solution, but I'm not coming up with the correct answer. Help!!!

College Algebra  john, Sunday, November 14, 2010 at 3:28am
2e^7x +4=4
2e^7x=0
e^7x=0
ln1=0
so 7x=1
x=1/7
v.easy

College Algebra  Lee, Sunday, November 14, 2010 at 3:45am
Yes this would be very simple, except this is a logarithim equation. The answer you gave isn't correct either.
the e actually represect ln.

LEE  College Algebra  Reiny, Sunday, November 14, 2010 at 10:41am
Lee, the solution that John gave you is correct according to the way you typed the question.
I have a feeling you meant to type
2e^(7x+4) = 4
if so, then
e^(7x+4) = 2
take ln of both sides
ln(e^(7x+4)) = ln2
(7x+4)lne = ln2 , but lne = 1
7x+4 = ln2
7x = ln2  4
x = (ln2  4)/7 or appr.  .4724

College Algebra  Lee, Tuesday, November 16, 2010 at 10:46pm
you are correct. I understand it now. You are such a fantastic help :)
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