these were my steps. Can someone tell me where have i goe wrong since the answer is $-{\frac 14}$.
$\sqrt{\log(\sqrt{10}a)} = {\frac 12}$
${\frac 12}{\log(\sqrt{10}a)} = \log\sqrt{10}$
${\log(\sqrt{10}a)}^{\frac 12} = {\log\sqrt10}$ because $(\log_ax^n = n\log_ax)$
$(\sqrt{10}a)^{\frac 12} = 10^{\frac 12}$ (squaring)
$10^{\frac 12}a = 10$ division by $10^{\frac 12}$
$ a = 10^{1-\frac 12}$
$a = \sqrt{10}$
$\sqrt{\log(\sqrt{10}a)}=\frac12$
$\log(\sqrt{10}a)=\frac14$
$\sqrt{10}a=10^{1/4}$
$a=10^{-1/4}$