Question

A equação x²-3x - 10 = 0 admite a:

a) raiz-5 b) raiz 2 c) raiz-2 d) raiz 4




12. 4)

d) raiz 4​

Answer 1

Explicação passo-a-passo:

$\sf x^2-3x-10=0$

$\sf \Delta=(-3)^2-4\cdot1\cdot(-10)$

$\sf \Delta=9+40$

$\sf \Delta=49$

$\sf x=\dfrac{-(-3)\pm\sqrt{49}}{2\cdot1}=\dfrac{3\pm7}{2}$

$\sf x'=\dfrac{3+7}{2}~\Rightarrow~x'=\dfrac{10}{2}~\Rightarrow~\red{x'=5}$

$\sf x"=\dfrac{3-7}{2}~\Rightarrow~x"=\dfrac{-4}{2}~\Rightarrow~\red{x"=-2}$

As raízes são 5 e -2

Letra C

Answer 2

Oie, Td Bom?!

■ Resposta: Opção C.

$x {}^{2} - 3x - 10 = 0$

• Coeficientes:

$a = 1 \: , \: b = - 3 \:, \: c = - 10$

• Fórmula resolutiva:

$x = \frac{ - b± \sqrt{b {}^{2} - 4ac} }{2a}$

$x = \frac{ - ( - 3)± \sqrt{( - 3 ){}^{2} - 4 \: . \: 1 \: . \: ( - 10)} }{2 \: . \: 1}$

$x = \frac{3± \sqrt{9 + 40} }{2}$

$x = \frac{3± \sqrt{49} }{2}$

$x = \frac{3±7}{2}$

$⇒x = \frac{3 + 7}{2} = \frac{10}{2} = 5$

$⇒ \frac{3 - 7}{2} = \frac{ - 4}{2} = - 2$

$S = \left \{ - 2 \:, \: 5 \right \}$

Att. Makaveli1996