Answer: (9x + 11i) (9x - 11i)
Explanation:
When i is squared, you are given a negative value, but by multiplying a positive by a negative, we reverse that and are left with positive 121. The 9x will be cancelled out by the 11's and squaring the 9x will give 81x^2.
It's hard to fully explain this, but if I do find something, I will update this or comment more explanation. You could try to solve using the quadratic formula.
Hope this helps.