“整体代换”的思想来解题,（因为把m,n都求出来显然是太麻烦了）m^2 + n^2 + 2mn = 7m^2 + n^2 - 2mn = 3,所以,m^2 + n^2 = 52mn=2 ,mn=1.m^4 + n^4= (m^2 + n^2)^2 - 2 * m^2 * n^2= (m^2 + n^2)^2 - 2 * (mn)^2= 5...