What method would I use? I am confused on how to solve it.

Bring the -20 over to the left so that it’s

9k² + 3 + 20 = 0 [reverse the sign when you carry over]
9k² + 23 = 0 [add the 3 and 20]

solve as a quadratic eqn and you’ll get
k = 0-1.59861050777i
or
k = 0+1.59861050777i

since there’s an i in the answers, it means this equation has no solution (or in terms of graphs, does not intercept/touch the x-axis)

hope this helped!