Как решать показательные уравнение и неравенства?

27*2^x-8*3^x=0

2^ (x+1) - 2^ (x-1) = 3^ (2-x)

9*4^x - 13*6^x + 4*9^x=0

1) 27*2^x-8*3^x=0 / 3^x

27 * (2/3) ^x - 8 = 0

(2/3) ^x = 8/27

(2/3) ^x = (2/3) ^3

x = 3

Ответ: х = 3

2) 2^ (x+1) - 2^ (x-1) = 3^ (2-x)

2 * (2^x) - (1/2) * (2^x) = 9 / (3^x)

(2^x) * (2 - 1/2) = 9 / (3^x)

(2^x) * (3/2) = 9 / (3/2)

(6^x) = 6^1

x = 1

Ответ: х = 1

3) 9 * (4^x) - 13 * (6^x) + 4 * (9^x) = 0

9 * (2^2x) - 13 * (2^x) * (3^x) + 4 * (3^2x) = 0 / (3^2x)

9 * (2/3) ^2x - 13 * (2/3) ^x + 4 = 0

(2/3) ^x = t

9t^2 - 13t + 4 = 0

D = 169 - 4*9*4 = 25

t1 = (13 - 5) / 18

t1 = 4/9

t2 = (13 + 5) / 18

t2 = 1

1) (2/3) ^x = 4/9

(2/3) ^x = (2/3) ^2

x1 = 2

2) (2/3) ^x = 1

(2/3) ^x = (2/3) ^0

x2 = 0

Ответ: x1 = 2; x2 = 1