[(a+b)^2+(a-b)^2][(m-n)^2+2mn]=（a^2+b^2+2ab+a^2+b^2-2ab)(m^2+n^2-2mn+2mn)=2(a^2+b^2)(m^2+n^2)=2[(am)^2+(bn)^2+(an)^2+(bm)^2]题目写错了一个字母,应为an+bm=4分别将两式平方相加25=（am-bn)^2+(an+bm)^2=(am...