Question

32) resolva a equação x^2-3x-18=0​

Answer 1

delta=9-4.1. (-18)

9+72=81 Raiz de 81 é 9

x=-b +- 9/2.a

x1=3+9=12/2=6

x2= 3-9=6/2=3

3^2-3.3-18=0

9-9-18

9-9=0

Answer 2

$\large\boxed{\boxed{\boxed{{Ol\'a}}}}}$

Sem mais delongas respondendo...

$x_{1},_{2}=\frac{-b±\sqrt{b^2-4.a.c}}{2.a}$

onde:

a = 1 ; b = —3 e c = —18

$x_{1},_{2}=\frac{3±\sqrt{(-3)^2-4.1.(-18)}}{2.1}$

$x_{1},_{2}=\frac{3±\sqrt{9+72}}{2}$

$x_{1},_{2}=\frac{3±\sqrt{81}}{2}$

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$x_{1}=\frac{3+13}{2}$

$x_{1}=\frac{16}{2}$

$x_{1}=8$$\checkmark$

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$x_{2}=\frac{3-13}{2.1}$

$x_{2}=\frac{-10}{2}$

$x_{2}=-5$$\checkmark$