1、原式=4+m²-6m+5=m²-6m+9=(m-3)²2、原式=(x²+2xy+y²)+xy=(x+y)²+xy=4²+2=18
①4+(m-1)(m-5)=4=m^2-6m+5=m^2-6m+9=(m-3)^2②x^2+y^2+3xy=(x+y)^2+xy=4^2+2=18
