x^2+y^2=13,xy=6,求x^4+y^4的值
问题描述:
x^2+y^2=13,xy=6,求x^4+y^4的值
答
x^4+y^4
=(x^2+y^2)^2-2x^2y^2
=13^2-2*(6)^2
=169-72
=97