9. `(x+0,7)^3 = -27`
`(x+0,7)^3 = (-3)^3`
`⇒ x+0,7 = -3`
`⇒ x = -3,7`
10. `(2/3x - 1/3)^5 = 1/243`
` ( 2/3x -1/3)^5 = (1/3)^5`
`⇒ 2/3x - 1/3 = 1/3`
`⇒ 2/3x = 2/3`
`⇒ x = 1`
11. `(2/5-3X)^2 = 9/25`
`(2/5-3x)^2 = (3/5)^2`
`⇒ 2/5 - 3x = 3/5`
`⇒ 3x = -1/5`
`⇒ x = -1/15`
12. ` (2x-1)^10 = 49^5`
`⇒ (2x-1)^10 = (7^2)^5 = 7^10`
`⇒ 2x-1=7`
`⇒ 2x=8`
`⇒ x = 4`
13. `x : 5^2 = (3/5)^2 : 3^2`
`x : 5^2 = (3/5 : 3)^2`
`x:5^2 = 1/25`
`x = 1`