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

2 Answers | Add Yours

justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

We have to solve: e^2x - 6e^x + 5 = 0

e^2x - 6e^x + 5 = 0

let e^x = t

=> t^2 - 6t + 5 = 0

=> t^2 - 5t - t + 5 = 0

=> t(t - 5) - 1( t - 5) = 0

=> (t - 1)(t - 5) = 0

=> e^x = 1 and e^x = 5

=> x = 0 and x = ln 5

The solution of the equation is x = 0 and x = ln 5

giorgiana1976's profile pic

giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

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}.

We’ve answered 318,989 questions. We can answer yours, too.

Ask a question