Answer:
![b\sqrt[n]{a}](https://tex.z-dn.net/?f=b%5Csqrt%5Bn%5D%7Ba%7D)
Step-by-step explanation:
It will probably be 196yd because the formulae to calculate the area of a square is any side^2 as a square has all equal sides and area = length times breath. Hope this is helpful.
Your question is not stated clearly but I think you are asking to find the sqrt{b} when 81 is the b.
You have two negatives together; this equals a positive.
So 4 + 19= 23