Verified answer

а⁻¹= 1/а

1) (1/7)^x = 7  

 (1/7)^x = (1/7)⁻¹

 х=-1

2) 5^-x = 25

  5^-x = 5²

  х= - 2

3) 27^x = 3

    3³ˣ =3¹

     х= 1/3

4) (1/25)^x = 5

     5⁻²ˣ =5¹

    х= -1/2

5) (2/3)^x * (2/3)^2x = 16/81

   (2/3)ˣ⁺²ˣ = (2/3)⁴

     3х=4

      х= 4/3 = 1 ¹/₃