Respostas

2014-06-28T13:44:26-03:00
2 x elevado a 2 menos x menos 1 me  ajudem

2x² - x - 1 = 0
a = 2
b = - 1
c = - 1
Δ = b² - 4ac
Δ = (-1)² - 4(2)(-1)
Δ = + 1 + 8
Δ = 9 -------------------------------√9 = 3
se
Δ > 0
então (baskara)

x = -b - + √Δ/2a
x' = -(-1) - √9/2(2)
x' = + 1 - 3/4
x' = - 2/4---------------ou   x =  - 1/2

x" = -(-1) + √9/2(2)
x" = + 1 + 3 /4
x" = 4/4
x" = 1
 
2 5 2
A melhor resposta!
2014-06-28T15:10:39-03:00
2x² - x - 1 = 0, p/ a = 2, b = -1 e c  = -1
Δ = (-1)² - 4(2)(-1)
Δ = 1 + 8 = 9
x' = [-(-1)+√9]/2.2 = (1 + 3)/4 = 4/4 = 1 
x" = [-(-1)-√9]/2.2 = (1 - 3)/4 = -2/4 = -1/2
S ={-1/2, 1}
2 5 2