25) (5m² + n²)(2m² -n²) =

25) Решим данное выражение:

$$ (5m^2+n^2)(2m^2-n^2) = 5m^2 \cdot 2m^2 - 5m^2 \cdot n^2 + n^2 \cdot 2m^2 - n^2 \cdot n^2 = 10m^4 - 5m^2n^2 + 2m^2n^2 - n^4 = 10m^4 - 3m^2n^2 - n^4 $$

Ответ: $$ 10m^4 - 3m^2n^2 - n^4 $$