Question

Cho x+2y=5. Tinh

B=x²+ 4y² -2x +10 +4xy -4y

Answer 1

\(B=\left(x^2+4xy+4y^2\right)-\left(2x+4y\right)+10\)

    \(=\left(x+2y\right)^2-2\left(x+2y\right)+10\)

    \(=5^2-2.5+10\)

      \(=25\)