3^(x^2 + y^2) = 81
log 2(x) + 2log 4(y) = 1
3^(x^2 + y^2) = 3^3
log 2(x) + 2log (2^2) (y) =1
x^2 + y^2 = 3
log 2(x) + 2/2 * log 2(y) = 1
x^2 + y^2 = 3
log 2(xy) = 1
x^2 + y^2 = 3
2^1 = xy
x^2 + y^2 = 3
xy = 2
x = 2/y
(2/y) * y = 2
2 = 2 => x и у - любые числа, не = 0