√[ 10 √(10a )] = 10^(1/2) * (10a)^(1/4) = 10^(1/2 + 1/4) * a*(1/4) =
10^(3/4) * a^(1/4)
So we have
10^(3/4) * a^(1/4) / 0.1 =
10^(3/4) * a^(1/4) / (1/10) =
10 * 10^(3/4) * a^(1/4) =
10^(7/ 4) * a^(1/4)
So
log [10^(7/ 4) * a^(1/4) ] =
log [ 10^(7/4) ] + log a ^(1/4) =
(7/4) log 10 + (1/4) log a =
(7/4) + log a / 4 =
[ 7 + log a ] / 4