Which condition ensures that all roots of the cubic equation x3+px+q=0x^3 + px + q = 0x3+px+q=0 are real?
4p3+27q2≤04p^3 + 27q^2 \leq 04p3+27q2≤0
p2+q2>0p^2 + q^2 > 0p2+q2>0
p>0p > 0p>0
q<0q < 0q<0