Respuesta :

we should know that
[tex] (a^{m} )^{n} = a^{m*n} [/tex]
125 = 5 * 5 * 5

so, the given expression can be rewritten as following
[tex] 125^{2x} = (5*5*5)^{2x} = ( 5^{3} )^{2x} = 5^{3*2x} =5^{6x} [/tex]