Answer:
The first option is the answer (k = +/- 2 square root of J)
Step-by-step explanation:
Since you need to leave k by itself, You multiply both sides by 4 which will leave you with 4J=k^2. To get rid of the square(^2), you need to square root both sides which will leave k by it self. So now you have 4J inside the square root = k. The last step is to take the square root of 4 (which is + or -2) and put it outside the square root sign, leaving J inside the square root.
