设a=m-3n,b=m-n,c=m+n,d=m+3n【等差设项技巧】则a+4=m-3n+4,b+3=m-n+3,c+3=m+n+3,d+5=m+3n+5(a+4)(c+3)=(b+3)²即(m-3n+4)(m+n+3)=(m-n+3)²整理得：-4n²+m+n+3=0【1】(b+3)(d+5)=(c+3)²即(m-n+3)...