合并下列各式的同类项①3m²n+5mn²+6nm²-4n²m-mn²②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
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![合并下列各式的同类项①3m²n+5mn²+6nm²-4n²m-mn²②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²](/uploads/image/z/5222956-4-6.jpg?t=%E5%90%88%E5%B9%B6%E4%B8%8B%E5%88%97%E5%90%84%E5%BC%8F%E7%9A%84%E5%90%8C%E7%B1%BB%E9%A1%B9%E2%91%A03m%26sup2%3Bn%2B5mn%26sup2%3B%2B6nm%26sup2%3B-4n%26sup2%3Bm-mn%26sup2%3B%E2%91%A13%28a%2Bb%29%26sup2%3B-%28a-b%29%2B2%28a%2Bb%29%26sup2%3B%2B4%28a-b%29-%28a%2Bb%29%26sup2%3B)
合并下列各式的同类项①3m²n+5mn²+6nm²-4n²m-mn²②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
合并下列各式的同类项
①3m²n+5mn²+6nm²-4n²m-mn²
②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
合并下列各式的同类项①3m²n+5mn²+6nm²-4n²m-mn²②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
①3m²n+5mn²+6nm²-4n²m-mn²
=(3+6)m²n+(5-4-1)mn²
=9m²n
②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
=(3+2-1)(a+b)²+(4-1)(a-b)
=4(a+b)²+3(a-b)
3m²n+5mn²+6nm²-4n²m-mn²
=3m²n+6nm²+5mn²-4n²m-mn²
=9m²n
3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
=3(a+b)²+2(a+b)²-(a+b)²-(a-b)+4(a-b)
=4(a+b)²+3(a-b)
合并下列各式的同类项
①3m²n+5mn²+6nm²-4n²m-mn²
=(3m^2n+6m^2n)+(5mn^2-4mn^2-mn^2)
=9m^2n
②3(a+b)²-(a-b)+2(a+b)²+4(a-b)-(a+b)²
=[3(a+b)^2+2(a+b)^2-(a+b)^2]+[-(a-b)+4(a-b)]
=4(a+b)^2+3(a-b)
1、把m(或n)都放前面,就看得出那些事同类项了
原式=3m²n+5mn²+6m²n-4mn²-mn²=3m²n+6m²n+5mn²-4mn²-mn²=9m²n
2、原式=3(a+b)²+2(a+b)²-(a+b)²-(a-b)+4(a-b)=4(a+b)²+3(a-b)
1.=(3m^2n+6m^2n)+(5mn^2-4mn^2-mn^2)
=9m^2n
2.=[3(a+b)^2+2(a+b)^2-(a+b)^2]+[-(a-b)+4(a-b)]
=4(a+b)^2+3(a-b)
1)9m²n
2)4(a+b)²+3(a-b)