Monday, September 8, 2014

Solve the equation.e^2x - 6e^x + 5 = 0

We'll apply substitution technique to solve the
exponential equation.


e^x =
t


We'll raise to square both
sides:


e^2x = t^2


t^2 - 6t + 5
= 0


We'll apply quadratic
formula:


t1 = [6+sqrt(36 -
20)]/2


t1 = (6 + 4)/2


t1 =
5


t2 = 1


But e^x = t1
=> e^x = 5


We'll take natural logarithms both
sides:


ln e^x = ln 5


x*ln e =
ln 5


x = ln 5


e^x =
t2=> e^x = 1


x =
0


The solutions of the equation are: {0 ; ln
5}.

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