Question 28: Let x+y=3. Calculate the value of the expression:\( A = {x^2} + 2xy + {y^2} – 4x – 4y + 1\)

\(\begin{array}{l} A = {x^2} + 2xy + {y^2} – 4x – 4y + 1 = \left( {{x^2} + 2xy + {y^2}} \right) – \left( {4x + 4y} \right) + 1 = {\left( {x + y} \right)^2} – 4\left( {x + y} \right) + 1\\ x + y = 3 \to A = {3^2} – 4.3 + 1 = – 2 \end{array}\)