If there is no real solution the Discriminant (b^2 - 4ac) will have a value less than zero. The a, b and c refer to the coefficients in the equation
ax^2 + bx + c = 0.
So for this equation to have no real solution 4^2 - 4*p * 6 < 0
-24p + 16 < 0
-24p < -16
p > 16/24
p > 2/3
So the value of p must be greater than 2/3 for no real solutions, (answer).