Can someone help me, I am stuck and do not know how to complete. Maybe my first part is wrong, I don't understand by looking at my example if I am doing it right or not.

Question

Square root Property

2k^2 +144=0

2k^2 +144-144=0-144
2k^2=-144
This is where I am confused
2k=sqrt -144 (?)

Answer 1

2k^2 = -144
k^2 = -72

Unless you have studied complex numbers you would stop here and say
"there is no real solution" since you cannot take the square root of a negative.

If you studied complex numbers you should know that i = √-1

so x = √-72
x = ±6√2 i