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3^2x-1+3^2x=108

2^x+1+2x-1+2^x=28

7^x-7^x-1=6

5^3x+3·5^3x-2=140

3^2x-1+3^2x=108

3^2x-1 (1+3) = 108

3^ (2x-1) = 27

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

2x-1=3

x=2

2^x+1+2x-1+2^x=28

2^ (x-1) (2^2+1+2) = 28

2^ (x-1) * 7=28

2^ (x-1) = 2^2

x-1=2

x=3

7^x-7^x-1=6

7^ (x-1) (7-1) = 6

7^ (x-1) = 1

x-1=0

x=1

5^3x+3·5^3x-2=140

5^ (3x-2) (5^2+3) = 140

5^ (3x-2) * 28=140

5^ (3x-2) = 5

3x-2=1

x=1