-2x^(3m+1)*y^(2n)*[7x^(n-6)*y^(-3-m)=-14x^(3m+1-6+n)y^(2n-3-m)x的4次方是同类项2n-3-m=03m+1-6+n=4解得m=15/7 n=9/7m²+n=225/49+63/49=288/49望采纳
