已知x2=x+1,y2=y+1,且x≠y.
来源:学生作业帮 编辑:百度作业网作业帮 分类:数学作业 时间:2024/06/07 06:31:31
已知x2=x+1,y2=y+1,且x≠y.
(1)求证:x+y=1;(2)求x5+y5的值.
(1)求证:x+y=1;(2)求x5+y5的值.
(1)证明:∵x2=x+1,y2=y+1,
∴x2-y2=x-y
∴x+y=1(x≠y)
(2)∵x2=x+1,y2=y+1,∴x3=x2+x,y3=y2+y,x4=x3+x2,y4=y3+y2,x5=x4+x3,y5=y4+y3,
∴x5+y5
=x4+x3+y4+y3
=x3+x2+x2+x+y3+y2+y2+y,
=x2+x+x2+x2+x+y2+y+y2+y2+y,
=3(x2+y2)+2(x+y),
=3(x+1+y+1)+2(x+y),
=3×3+2,
=11.
∴x2-y2=x-y
∴x+y=1(x≠y)
(2)∵x2=x+1,y2=y+1,∴x3=x2+x,y3=y2+y,x4=x3+x2,y4=y3+y2,x5=x4+x3,y5=y4+y3,
∴x5+y5
=x4+x3+y4+y3
=x3+x2+x2+x+y3+y2+y2+y,
=x2+x+x2+x2+x+y2+y+y2+y2+y,
=3(x2+y2)+2(x+y),
=3(x+1+y+1)+2(x+y),
=3×3+2,
=11.
已知x2=x+1,y2=y+1,且x≠y.
2010.09.已知x、y为实数,且(x2+y2)(x2+y2+1)=20,求x2+y2的值
已知集合a=(x,y)/x,y∈R 且x2+y2=1
已知x>y>0,且xy=1,求 (x2+y2)/(x-y)的最小值,
1.已知集合a=(x,y)/x,y∈R 且x2+y2=1 已知集合a=(x,y)/x,y∈R,且x
已知x,y为正数,且x2+ y2/2=1,则x√1+y2的最大值?
已知x-y=1,求x2-y2+x-3y的值.
已知x2+y2=25,x+y=7,且x>y,求x-y.
已知x、y为实数,且(x2+y2)(x2+y2+1)=20,求x2+y2的值 过程
已知x>y,且xy=1,求证:(x2+y2/x-y)≥2根号2
已知[(x2+y2)-(x-y)2+2y(x-y)]÷4y=1,求4x/4x2-4y2-1/2x+y的值,
已知x2-2xy=3y2且x,y为非零实数 求:(1)2x+y/x-2y (2)2x2-3y2+5xy/x2+xy+y2