Question

dada a função definida por
$f(x) = {x }^{2} + x - 2$
calcule o valor de x quando:
$f(x) = 0$


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Answer 1

Resposta: X = 1 ou X = -2

$x = \frac{-b+-\sqrt{b^{2}-4ac } }{2a}\\\\x = \frac{-1+-\sqrt{1^{2}-4*1*-2 } }{2*1}\\\\x = \frac{-1+-\sqrt{1+8} }{2}\\\\x = \frac{-1+-\sqrt{9} }{2}\\\\\left \{ {{x_1=\frac{-1+3}{2}=\frac{2}{2}=1  } \atop {x_2=\frac{-1-3}{2}=\frac{-4}{2} = -2  }} \right.$