Solve for x:!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Question

 e^2x-5e^x+4=0 and solve 12^x=5^x+4?

 

Answer 1

1)Given that e^2x - 5e^x + 4 = 0

  Let e^x = y

  y^2 - 5y + 4 = 0

  y^2 - 4y - y + 4 = 0

  y(y - 4) -1(y - 4) = 0

 Take (y - 4) as common

 (y - 4) (y - 1) =0

 (y - 4) = 0 ==> y = 4

 (y - 1) = 0 ==> y = 1

 y = e^x = 4 ==> x = log(4)

 y = e^x = 1 ==> x = 0