\(\begin{array}{l}b)\,{\left( {2x + 1} \right)^2} + {\left( {2x - 1} \right)^2} - 2.\left( {1 + 2x} \right)\left( {1 - 2x} \right)\\ = {\left( {1 + 2x} \right)^2} + {\left( {1 - 2x} \right)^2} - 2.\left( {1 + 2x} \right)\left( {1 - 2x} \right)\\ = {\left( {1 + 2x - 1 + 2x} \right)^2}\\ = {\left( {4x} \right)^2}\\tai\,\,\,x = 100\\ \Rightarrow {\left( {4.100} \right)^2} = {16.100^2} = 16.10000 = 160000\end{array}\)
\(\begin{array}{l}d)\,8{x^3} - 60{x^2} + 150x - 125\,\,\,tai\,\,x = 4\\ = {\left( {2x} \right)^3} - 3.{\left( {2x} \right)^2}.5 + 3.2x{.5^2} - {5^3}\\ = {\left( {2x - 5} \right)^3}\\tai\,\,\,x = 4\\ \Rightarrow {\left( {2x - 5} \right)^3} = {\left( {2.4 - 5} \right)^3} = {3^3} = 27\end{array}\)
