(1,5 điểm) Tìm x , biết: a) 2 x + 2 0 = 3 5 : 3 3 . b) 99 − ( 5 − 3 x ) = − 2. c) 2 ( x − 6 ) 2 − 1 = 49.

a) \(2x + {2^0} = {3^5}:{3^3}\)

\(2x + 1 = {3^2}\)

\(2x + 1 = 9\)

\(2x = 8\)

 \(x = 4\).

Vậy \(x = 4.\)

b) \(99 - \left( {5 - 3x} \right) = - 2\)

\(5 - 3x = 99 - \left( { - 2} \right)\)

\(5 - 3x = 101\)

\(3x = 5 - 101\)

\(3x = - 96\)

\(x = - 32\)

Vậy \(x = - 32\).

c) \(2{\left( {x - 6} \right)^2} - 1 = 49\)

\(2{\left( {x - 6} \right)^2} = 50\)

       \({\left( {x - 6} \right)^2} = 25\)

Trường hợp 1:

\(x - 6 = 5\)

\(x = 11\)

Vậy \(x \in \left\{ {11;\,\,1} \right\}\).

Trường hợp 2:

\(x - 6 = - 5\)

\(x = 1\)