Question

Să se rezolve in C ecuatia: x^3+8=0

Answer 1

x^3+2^3=0
(x+2)(x^2-2x+2^2)=0
x+2=0 sau x^2-2x+4=0
x=-2. a=1
b=-2
c=4

∆=b^2-4ac=(-2)^2-4·1·4=4-16=-12

x1;x2=(-b ± i√-∆)/2a= (2±i√12)/2= (2±2i√3)/2=[2(1±i√3)]/2=1±i√3

x1=1+i√3
x2=1-i√3

Answer 2

(x+2)(x²-2x+4)=0
x1=-2∈R⊂C
x2,3=(2+-√(4-16)/2=(2+-2√3 i)/2=1+-1√3
as simple as that!!!