Question

Para que a função definida por ƒ(x) = |x² – 4x| tenha sua imagem igual a 12, x deve assumir os valores

Answer 1

$|x^2-4x|=12\\\\x^2-4x=12\ ou\ x^2-4x=-12\\\\x^2-4x-12=0\ ou\ x^2-4x+12=0\\\\\Delta=16+48=64\ ou\ \Delta=16-48=-32\\\\\\x=\dfrac{4\pm8}{2}\\\\\\x=6\ ou\ x=-2$