SOLUTION: Solve the equation by rewriting the exponential expressions using the indicated logarithm. e^4x = 19 using the natural log 60^e−0.12t = 10 using the natural log *Kno

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: Solve the equation by rewriting the exponential expressions using the indicated logarithm. e^4x = 19 using the natural log 60^e−0.12t = 10 using the natural log *Kno      Log On


   



Question 1129238: Solve the equation by rewriting the exponential expressions using the indicated logarithm.
e^4x = 19 using the natural log
60^e−0.12t = 10 using the natural log
*Knowing that the natural log base is 10 the answers that I came up with was: log10=19, but I don't know where the 4 is suppose to go. The same confusion goes for the second one, I thought the equation should be set up as log10=10, but I don't know where 60 and e^-0.12t goes. Can someone explain how to properly set up the equation? Thanks.

Found 3 solutions by Alan3354, ankor@dixie-net.com, MathTherapy:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the equation by rewriting the exponential expressions using the indicated logarithm.
e^4x = 19 using the natural log
Is the exponent 4? Or 4x?
-------------
60^e-0.12t = 10
Is the exponent -0.12 ?
Or -0.12t ?

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the equation by rewriting the exponential expressions using the indicated logarithm.
:
the natural log base is not 10, it's e, base ten is the "common log"
:
assuming
e%5E%284x%29+=+19 using the natural log
the log equiv of exponents
4x*ln(e) = ln(19)
the ln of e = 1, therefore
4x = ln(19)
4x = 2.4999
x = 2.4999%2F4
x = .7361
:
60%5Ee+-+.12t+=+10
60%5Ee+=+12t+%2B+10
using the natural logs
e*ln(60) = ln(12t + 10)
using calc: find e*ln(60)
11.13 = ln(12t+10)
find the e^x of both sides
68186.37 = 12t + 10
subtract 10 from both sides
68176.37 = 12
t = 68176%2F12
t = 5681.36

Answer by MathTherapy(10555) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the equation by rewriting the exponential expressions using the indicated logarithm.
e^4x = 19 using the natural log
60^e−0.12t = 10 using the natural log
*Knowing that the natural log base is 10 the answers that I came up with was: log10=19, but I don't know where the 4 is suppose to go. The same confusion goes for the second one, I thought the equation should be set up as log10=10, but I don't know where 60 and e^-0.12t goes. Can someone explain how to properly set up the equation? Thanks.
a)  If it's matrix%281%2C3%2C+e%5E%284x%29%2C+%22=%22%2C+19%29, then:
matrix%281%2C3%2C+4x%2C+%22=%22%2C+ln+%2819%29%29 ----- Converting to NATURAL LOGARITHMIC (ln) form

b) If it's matrix%281%2C3%2C+60%5E%28e+-+.12t%29%2C+%22=%22%2C+10%29, then:
matrix%281%2C3%2C+ln+%2860%5E%28e+-+.12t%29%29%2C+%22=%22%2C+ln+%2810%29%29 ----- Taking the NATURAL LOG (ln) of each side
matrix%281%2C3%2C+%28e+-+.12t%29+%2A+ln+%2860%29%2C+%22=%22%2C+ln+%2810%29%29
matrix%281%2C3%2C+e+-+.12t%2C+%22=%22%2C+ln+%2810%29%2Fln+%2860%29%29
matrix%281%2C3%2C+-+.12t%2C+%22=%22%2C+ln+%2810%29%2Fln+%2860%29+-+e%29

OR
b) If it's matrix%281%2C3%2C+60%5Ee+-+.12t%2C+%22=%22%2C+10%29, then you DO NOT NEED to use REGULAR or NATURAL LOGS to solve. Do as follows:
matrix%281%2C3%2C+-+.12t%2C+%22=%22%2C+10+-+60%5Ee%29

That's ALL!!