Tìm (x), biết:

a) \(928 - \left( {31 + x} \right) = 128\)

\(31 + x = 928 - 128\)

\(31 + x = 800\)

\(x = 800 - 31\)

\(x = 769\)

Vậy \(x = 769\).

b) \(8 - 2x =  - 4\)

\(2x = 8 - \left( { - 4} \right)\)

\(2x = 12\)

\(x = 6\)

Vậy \(x = 6\).

c) \({\left( {4x - 11} \right)^6} = {25^3}\)

\({\left( {4x - 11} \right)^6} = {\left( {{5^2}} \right)^3}\)

\({\left( {4x - 11} \right)^6} = {5^6} = {\left( { - 5} \right)^6}\)

Trường hợp 1:

\(4x - 11 = 5\)

\(4x = 16\)

\(x = 4\)

Vậy \(x \in \left\{ {4;1,5} \right\}\).

ường hợp 2:

\(4x - 11 =  - 5\)

\(4x = 6\)

\(x = 1,5\)