Odpowiedź i wyjaśnienie:
a) - 6x² - 7x + 5 = 0
a = - 6, b = - 7 , c = 5
∆ = b² - 4 * a * c
∆ = (-7)² - 4 * (-6)* 5 = 49 + 120 = 169
√∆ = 13
x1 = (-b -√∆)/2a
x1 = (7 - 13)/-12 = -6/-12 = ½
x2= (-b +√∆)/2a
x2 = ( 7 + 13)/- 12 = 20/-12 = - 1 ⅔
Odp : x = ½ v x = - 1 ⅔.
b) - 2x² + x - 4 = 0
a = - 2, b = 1, c = -4
∆ = 1² - 4 * (-2) * ( -4) = 1 - 32 = - 31
∆ < 0
Odp : Równanie nie ma rozwiązania.
c) - x² + 2x - 1 = 0
a = - 1 , b = 2, c = - 1
∆ = b² - 4 * a* c
∆ = 2² - 4 * (-1) * (-1) = 4 - 4 = 0
xo = -b/2a
xo = - 2/ - 2 = 1
Odp: x = 1
