Question

разложить на множители
9(m+n)^2-(m-n)^2

Answer 1

$9(m+n)^{2}-(m-n)^{2}\\a^{2}-b^{2}=(a-b)(a+b)\\(3(m+n))^{2}-(m-n)^{2}=(3(m+n)-(m-n))(3(m+n)+(m-n))\\=(3m+3n-m+n)(3m+3n+m-n)=(4n+2m)(4m-2n)$