Algebra Solve

Question

e^x+e^-x=7

Answer 1

e^x + e^-x = 7

e^2x + 1 = 7e^x        multiply both sides by e^x

e^2x - 7e^x + 1 = 0   subtract 7e^x form both sides

let u = e^x

u² - 7u + 1 = 0     substitution

 

Solve for u with Quadratic Formula.