问题标题：
已知m-2n=3.求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值.已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b的值
问题描述：
已知m-2n=3.求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值.
已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b的值
黄海风回答：
[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷(1/3)m=[9m²-4n²-5m²+2mn-10mn+4n²]÷(1/3)m=[4m²-8mn]÷(1/3)m=4m(m-2n)÷(1/3)m=12*(3)=36[(a²+b²)+2b(a-b)-(a-b)²]÷4b=[a²+b&su...
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