Question

已知(m+n)x^n·y^m-2·(3xy^2+5x^2·y)=21x^m·y^n+1+35x^m+1·y^n,求m和n

Answer 1

(m+n)x^n·y^m-2·(3xy^2+5x^2·y)=21x^m·y^n+1+35x^m+1·y^n

3(m+n)x^n+1·y^m+5(m+n)x^m+1·y^n=21x^m·y^n+1+35x^m+1·y^n

同类项系数相等

所以3(m+n)=21

5(m+n)=35

m+n=7

求不出具体的m和n