Question

Qual a solução de x²+8x-180=0 ?

Answer 1

x²= 2x

ou seja:

2x+8x iagual a : 10x

10 dividido por 180 

-18

Answer 2

Observe que:

 

$\text{x}=\dfrac{-\text{b}\pm\sqrt{\text{b}^2-4\cdot\text{a}\cdot\text{c}}}{\dfrac{2\cdot\text{a}}$

 

Onde,  $\Delta=\text{b}^2-4\cdot\text{a}\cdot\text{c}$

 

Segundo o enunciado, $\text{a}=1, \text{b}=8$ e $\text{c}=-180$

 

Desta maneira, $\Delta=8^2-4\cdot1\cdot(-180)=64+720=784$

 

Logo:

 

$\text{x}=\dfrac{-8\pm\sqrt{784}}{2\cdot1}=\dfrac{-8\pm28}{2}$

 

As raízes são:

 

$\text{x}=\dfrac{-8+28}{2}=\dfrac{20}{2}=10$

 

$\text{x}=\dfrac{-8-28}{2}=\dfrac{-36}{2}=-18$