Question

Rozwiąż równanie : x^3 - 3x -2 =0

Answer 1

x^3 - x - 2x - 2 = 0

x(x^2 - 1) - 2( x + 1) = 0

x(x - 1)(x + 1) - 2(x + 1) = 0

(x + 1) [ x(x - 1) - 2 ] = 0

x + 1 = 0 lub x^2 - x - 2 = 0

x = -1 lub

 

delta = 1 + 8 = 9

x1 = (1 - 3) / 2 = -1

x2 = 4/2 = 2

 

odp. x = -1 (dwukrotny pierwiastek) i x = 2