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已知m-2n=3.求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3 m 的值.

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已知m-2n=3.求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3 m 的值.
已知 2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b的值
[(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+b²+2ab-2b²-a²+2ab-b²]÷4b
=[4ab-2b²]÷4b
=2b(2a-b)÷4b
=2*(5)÷4
=5/2