Question

$y = - { x}^{2} + 9$
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Answer 1

Resposta:

$y=-x^2+9\\ \\ -x^2+9=0\\ \\ -x^2=-9~~~\times(-1)\\ \\ x^2=9\\ \\ x=\pm\sqrt{9} \\ \\ x=\pm3\\ \\ V=\{-3,+3\}$