Question

Escriba x2 + y2 +4x -8y +4= 0 determinar el centro y el radio
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Answer 1

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

Centro:

$C( - 2,4)$

Radio:

${r}^{2} = 16 \\ r = \sqrt{16} \\ r = 4$

Espero haberte ayudado :)

Éxitos.