Tìm (x), biết:

a) \(38 - 2x = 14\)

\(2x = 38 - 14\)

\(2x = 24\)

\(x = 12\)

Vậy \(x = 12\).

b) \[3\left( {x - 1} \right) + 25 =  - 2\]

\[3\left( {x - 1} \right) =  - 27\]

\(x - 1 =  - 9\)

\(x =  - 8\)

Vậy \(x =  - 8\).

c) \({3^{x + 2}} + {3^x} = 10\)

\({3^x}{.3^2} + {3^x} = 10\)

\({3^x}.\left( {{3^2} + 1} \right) = 10\)

\({3^x}.10 = 10\)

\({3^x} = 1\)

\({3^x} = {3^0}\)

Suy ra \(x = 0\).

Vậy \(x = 0\).