Question

Решите уравнение.

Answer 1

${x}^{2} + {y}^{2} + 4x - 8y + 20 = 0 \\ ({x}^{2} + 4x + 4) + ( {y}^{2} - 8y + 16) = 0 \\ {(x + 2)}^{2} + {(y - 4)}^{2} = 0 \\ x + 2 = 0 \\ x = - 2 \\ y - 4 = 0 \\ y = 4 \\ ( - 2;4)$