Indices Part-2

64 is 2^6 and sqrt of 2^(6×2) is 2^6, which is 64.

$\sqrt{2^a} = 64 \implies 2^{\frac {a}{2}} = 2^6$

Equating the exponents:

$\frac {a}{2} = 6 \implies a = 6 \times 2 = \boxed {12}$