Question

упростить выражение (5m+4n)(4n-5m)+25m²

Answer 1

1.20mn-25m^2+16n^2-20mn+25m^2
2. 16n^2

Answer 2

$(5m+4n)(4n-5m)+25m^2=((4n)^2-(5m)^2)+25m^2 =\\=16n^2-25m^2+25m^2=16n^2$