已知m²-mn=21,mn-n²=-15,求m²-n²和m²-2mn+n²的值.(要解题思路)
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![已知m²-mn=21,mn-n²=-15,求m²-n²和m²-2mn+n²的值.(要解题思路)](/uploads/image/z/3016321-25-1.jpg?t=%E5%B7%B2%E7%9F%A5m%26%23178%3B-mn%3D21%2Cmn-n%26%23178%3B%3D-15%2C%E6%B1%82m%26%23178%3B-n%26%23178%3B%E5%92%8Cm%26%23178%3B-2mn%2Bn%26%23178%3B%E7%9A%84%E5%80%BC.%EF%BC%88%E8%A6%81%E8%A7%A3%E9%A2%98%E6%80%9D%E8%B7%AF%EF%BC%89)
已知m²-mn=21,mn-n²=-15,求m²-n²和m²-2mn+n²的值.(要解题思路)
已知m²-mn=21,mn-n²=-15,求m²-n²和m²-2mn+n²的值.(要解题思路)
已知m²-mn=21,mn-n²=-15,求m²-n²和m²-2mn+n²的值.(要解题思路)
m²-mn=21,mn-n²=-15
两式相加得
m²-n²=6
m²-mn=21,mn-n²=-15
两式相减
m²-2mn+n²=36