已知m的2次方=a-n,n的2次方=a+m,当m+n≠0,则a-mn的值为

m²=a-n (1)n²=a+m (2)(1)-(2)m²-n²=-n-m(m+n)(m-n)+(m+n)=0(m+n)(m-n+1)=0m+n≠0,只有m-n+1=0 n=m+1,代入(1)m²=a-(m+1)a=m²+m+1a-mn=m²+m+1-m(m+1)=m²+m+1-m²-m=1...