(1/2m-n)×(1/2m+n)×(1/4m^2-n^2)
=1/(2m-n) ×1/(2m+n) × 1/(4m^2-n^2)
=1/(2m-n)(2m+n) × 1/(4m^2-n^2)
=1/(4m^2-n^2) × 1/(4m^2-n^2)
=1/ (4m^2-n^2)^2
(1/2m-n)×(1/2m+n)×(1/4m^2-n^2)
=1/(2m-n) ×1/(2m+n) × 1/(4m^2-n^2)
=1/(2m-n)(2m+n) × 1/(4m^2-n^2)
=1/(4m^2-n^2) × 1/(4m^2-n^2)
=1/ (4m^2-n^2)^2