#(x^-4y^-2*x^2y^-4)^2#
#=>(x^-4y^-2*x^2y^-4)^2#
#a^n*a^m=a^(n+m),#multiplying as per this equation within the brackets.
#=>(x^-4*x^2*y^-2*y^-4)^2#
#=>(x^(-4+2)*y^(-2+ -4))^2#
#=>(x^-2*y^(-2-4))^2#
#=>(x^-2*y^-6)^2#
#(x^n)^m=x^(n*m),#so #(x^n*y^p)^m=x^(n*m)*y^(p*m),# from this we can simply the equation as#:#
#=>x^(-2*2)*y^(-6*2)#
#=>x^-4*y^-12#