Question

Es el radio de la circunferencia x^2+y^2-4=0

Answer 1

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