Respostas

2013-05-27T18:45:20-03:00

x² - 7x + 12 = 0

 

Aplicando Baskhara:

 

- (-7) +- {49-4.1.12} / 2.1 = 0

+7 +- {1} / 2 = 0

7 +- 1 /2 = 0 

Logo,

  x=4 ou  x=3

 

Segunda:

 

2x² + 5x - 3 = 0

 

Aplicando Baskhara:

 

-5 +- {25 - 4.2. (-3)} / 2.2 = 0

-5 +- {49} / 4 = 0

-5 +- 7 / 4 = 0

Logo,

  x=-3 ou  x=1/2

  • Usuário do Brainly
2013-05-27T23:10:01-03:00

a) \text{x}^2-7\text{x}+12=0

 

\text{x}=\dfrac{-(-7)\pm\sqrt{(-7)^2-4\cdot1\cdot12}}{2\cdot1}=\dfrac{7\pm1}{2}

 

\text{x}'=\dfrac{7+1}{2}=4

 

\text{x}"=\dfrac{7-1}{2}=3

 

 

b) 2\text{x}^2+5\text{x}-3=0

 

\text{x}=\dfrac{-5\pm\sqrt{5^2-4\cdot2\cdot(-3)}}{2\cdot2}=\dfrac{-5\pm7}{4}

 

\text{x}'=\dfrac{-5+7}{4}=\dfrac{1}{2}

 

\text{x}"+\dfrac{-5-7}{4}=-3