Question

Para quais valores reais de x a função y= x²-10x+21 é negativa??????
me ajudem

Answer 1

Resolução da questão, veja como fica:

$x^{2}-10x + 21 \ \textless \ 0\\\\\\\\ x = -b~\pm~\dfrac{\sqrt{b^{2}-4~\cdot~a~\cdot~c~}}{2~\cdot~a}}\\\\\\\ x = 10~\pm~\dfrac{\sqrt{(-10)^{2}-4~\cdot~1~\cdot~21}}{2~\cdot~1}}\\\\\\\ x = 10~\pm~\dfrac{\sqrt{100-84}}{2}\\\\\\\ x = 10~\pm~\dfrac{\sqrt{16}}{2}}\\\\\\\ x = 10~\pm~\dfrac{4}{2}}\\\\\\ x' = \dfrac{10+4}{2}}\\\\\\ x' = \dfrac{14}{2}}\\\\\\ \large\boxed{\boxed{\boxed{x' = 7.}}}}}}}}\\\\\\\ x'' = \dfrac{10-4}{2}}\\\\\\ x'' = \dfrac{6}{2}}\\\\\\ \large\boxed{\boxed{\boxed{x'' = 3.}}}}}\\\\\\\\ 3 \ \textless \ x\ \textless \ 7.$

Espero que te ajude. :).

Answer 2

Resposta:

depende

Explicação passo-a-passo: