Respuesta :

gmany

[tex]F(x)=3x^2-4\\\\F(a)=8\to3a^2-4=8\qquad\text{add 4 to both sides}\\\\3a^2=12\qquad\text{divide both sides by 3}\\\\a^2=4\to a=\pm\sqrt4\to a=\pm2\\\\Answer:\ \boxed{A.\ \pm2}[/tex]

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