Find the range of kkk such that the inequality x2+2kx+4k+5>0x^2 + 2kx + 4k + 5 > 0x2+2kx+4k+5>0 holds for all real xxx.
k<−5k < -5k<−5 or k>1k > 1k>1
−1<k<5-1 < k < 5−1<k<5
1<k<51 < k < 51<k<5
k<1k < 1k<1 or k>5k > 5k>5