Question

I want to know If I am correct.

1) x^3+27=0 x=-3
2) 8x^3-1=0 x=1/2
3) x^4+21x^2-100=0 x=2, -2 , 5i, -5i
4) 2x^3+3x^2-8X-12=0 x=2, -2 , -3/2
Are these correct?

Answer 1

first one is right

Answer 2

second one is right

Answer 3

third one is right

Answer 4

fourth one is also right
4 for 4