9(m+n)^2-16(m-n)^2=?

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9(m+n)^2-16(m-n)^2=?9(m+n)^2-16(m-n)^2=?9(m+n)^2-16(m-n)^2=?9(m+n)^2-16(m-n)^2=[3(m+n)]^2-[4(m-n)]^2

9(m+n)^2-16(m-n)^2=?
9(m+n)^2-16(m-n)^2=?

9(m+n)^2-16(m-n)^2=?
9(m+n)^2-16(m-n)^2=[3(m+n)]^2 - [4(m-n)]^2
根据平方差公式
=[3(m+n)+4(m-n)][3(m+n)-4(m-n)]
=[3m+3n+4m-4n][3m+3n-4m+4n]
=(7m-n)(-m+7n)
=-7m^2+50mn-7n^2

9(m+n)^2-16(m-n)^2
=[3(m+n)+4(m-n)]×[3(m+n)-4(m-n)]
=(3m+3n+4m-4n)×(3m+3n-4m+4n)
=(7m-n)(7n-m)