Respostas

2014-01-27T20:42:20-02:00
Δ = b² -4ac
Δ = (-4)² -4 *1 * (-5)
Δ = 16 + 20
Δ = 36
x' = (-b + √∆)/ 2a
(-(-4) + 6)/2 * 1
(4 + 6)/2
10/2
5
x'' = (-b - √∆)/ 2a
(-(-4) - 6)/2 * 1
(4 - 6)/2
-2/2
-1


S= {-1,5}
1 5 1
A melhor resposta!
2014-01-27T20:45:51-02:00
Na equação a=1 , b= - 4 e c= - 5
x^2 - 4x -5=0\\\\
x=\dfrac{4 \pm \sqrt{(-4)^2-4\cdot1\cdot(-5)}}{2}=\\\\
=\dfrac{4\pm\sqrt{36}}{2}\\\\
x_1=\dfrac{4+6}{2}=5\\\\
x_2=\dfrac{4-6}{2}=-1
1 5 1