Answer:
k = 9 and k = -9
Explanation:
Step 1: Take the square root of both sides to solve for k:
√(81) = √(k^2)
9 = k and 9 = k.
Note that there are two solutions for k since squaring both a positive and negative number gives us a positive number.
We can prove this by using 9 and -9 as an example:
9 * 9 = 81
-9 * -9 = 81.