Answer:
[tex]k = 6[/tex]
Step-by-step explanation:
[tex]x {}^{2} + kx + 9 = 0[/tex]
here,
a = 1,
b = k
c = 9
now,
[tex]D = b {}^{2} - 4ac[/tex]
[tex] k {}^{2} - 4(1)(9) = 0 \\ k {}^{2} - 36 = 0 \\ k {}^{2} = 36 \\ k = 6[/tex]
