решите x^log x по снованию 3=81

x^log3(x) = 81
logx(81) = log3(x)
logx(81) = logx(x) / logx(3)
logx(81) = 1 / logx(3)
4*logx(3)*logx(3) = 1
(logx(3))^2 = 1/4
logx(3) = 1/2
корень(x) = 3
x = 9