Упростите выражение: (m-3n)(m+3n)-(m-3n)^2

Question

Упростите выражение: (m-3n)(m+3n)-(m-3n)^2

Answer 1

(m-3n)(m+3n)-(m-3n)(m+3n)

Comments

(m-3n)(m+3n)-(m-3n)^2=m^2-9n^2-(m^2-6mn+9n^2)=m^2-9n^2-m^2+6mn-9n^2=6mn