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

x^4+y^4
=(x^2+y^2)^2-2x^2y^2
=13^2-2*(6)^2
=169-72
=97