Determine the set of values for kkk such that x2+kx+9>0x^2 + kx + 9 > 0x2+kx+9>0 holds for all real xxx.
k∈(−6,6)k \in (-6, 6)k∈(−6,6)
k∈[−6,6]k \in [-6, 6]k∈[−6,6]
k>6k > 6k>6
k<−6k < -6k<−6