若x=1⼀2(根号5-根号2),y=1⼀2(根号5+根号2)则 1、x^2+2xy+y^2 2、x分之y-y分之x

2024-12-23 06:22:12
推荐回答(2个)
回答1:

x+y=√5
y-x=√2
xy=3/4
1)
x^2+2xy+y^2
=(x+y)^2
=(√5)^2
=5

2)
y/x-x/y
=(y^2-x^2)/xy
=(y+x)(y-x)/xy
=√5*√2/(3/4)
=4√10/3

回答2:

x+y=√5
x-y=-√2
xy=3/4
x^2+2xy+y^2 =(x+y)²=5

y/x - x/y =(y²-x²)/ xy =(x+y)(y-x) / xy = √10/(3/4)=4√10/ 3