(4а+9b)²+(2+9b)*(2-9b)=0
16a²+72ab+81b²+4-81b²=0
16a²+72ab+4=0 :4
4a²+18ab+1=0
18ab=-1-4a²
b=(-1-4a²)/18a
(4а+9b)²+(2+9b)*(2-9b)=0
16a²+72ab+81b²+4-81b²=0
16a²+72ab+4=0 :4
4a²+18ab+1=0
18ab=-1-4a²
b=(-1-4a²)/18a
16+72в+81в²+4-81в²=0
72в+20=0
72в=-20
в=-20:72
в=-5/18
ответ:-5/18