\(a){\left( {x + \dfrac{1}{2}} \right)^2} = {x^2} + 2.x.\dfrac{1}{2} + {\left( {\dfrac{1}{2}} \right)^2} = {x^2} + x + \dfrac{1}{4}\)
\(b){\left( {2{\rm{x}} + y} \right)^2} = {\left( {2{\rm{x}}} \right)^2} + 2.2{\rm{x}}.y + {y^2} = 4{{\rm{x}}^2} + 4{\rm{x}}y + {y^2}\)
\(c){\left( {3 - x} \right)^2} = {3^2} - 2.3.x + {x^2} = 9 - 6{\rm{x}} + {x^2}\)
\(d){\left( {x - 4y} \right)^2} = {x^2} - 2.x.4y + {\left( {4y} \right)^2} = {x^2} - 8{\rm{x}}y + 16{y^2}\)