Think of the binomial squared as its own squared term.
Since the squared term is isolated, we can take the square root of both sides.
On the left, the square root removes the square and we have x + 7.
On the right, the square root of 81 is ± 9.
*Always use plus or minus when taking square root of both sides*
So we have x + 7 = ± 9.
Now, split things up into two separate equations.
Solving each equation from here, we find that x = -2 or x = 16.
We can write this as {-2, 16}.
