已知x+y=5,xy=2求x^8+y^8的值
问题描述:
已知x+y=5,xy=2求x^8+y^8的值
答
x^2+y^2=(x+y)^2-2xy=21,x^4+y^4=(x^2+y^2)^2-2X^2y^2=433,x^8+y^8=(x^4+y^4)-2x^4y^4=187457
已知x+y=5,xy=2求x^8+y^8的值
x^2+y^2=(x+y)^2-2xy=21,x^4+y^4=(x^2+y^2)^2-2X^2y^2=433,x^8+y^8=(x^4+y^4)-2x^4y^4=187457