已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路

来源：学生作业帮助网编辑：六六作业网时间：2024/12/26 12:24:21

已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路解x+y

已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路
已知x+y=8,xy=12,求x2+y2;(x-y)2的值
要思路

已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路
解
x+y=8
两边平方
(x+y)²=64
即x²+2xy+y²=64
∵xy=12
∴x²+y²+24=64
∴x²+y²=40
(x-y)²
=(x+y)²-4xy
=8²-4×12
=64-48
=16

要过程吗？
x=2,y=6 x^2+y^2=4+36=40 (x-y)^2=16

x2+y2=（x+y）^2-2xy
(x-y)2=（x+y）^2-4xy
给思路不给答案

x2+y2
=（X+Y）²-2XY
=8²-2×12
=64-24
=40
(x-y)2
=X²-2Xy+Y²
=X²+2Xy+Y²-4Xy
=（X+Y）²-4XY
=8²-4×12
=64-48
=16

已知x+y=8,xy=12,求(1)x2y+xy2(2)x2-xy+y2(3)x-y 已知x+y=5,xy=-12,求代数式x2-xy+y2 已知X2+Y2+8X+6Y+25=0 求代数式X2++XY+4Y2分之X2-4Y2 减X+2Y分之X的值已知x2+y2+4x-2y+5=0,求x2+2xy+y2值已知x2+y2,x-y=5,求x2+y2和xy的值. 已知x/y+y/x=2,求(x2+xy+y2)/(x2-4xy+y2)的值已知x2+xy=12,xy+y2=15,求(x+y)2-(x+y)(x-y)的值已知x+y=8,xy=12,求x2+y2;(x-y)2的值要思路已知X/Y=2/7, 求X2-3XY+2Y2/2X2-3XY+7Y2的值已知X2-2x+y2+6y+10=0,求（x2-2xy）/(xy+y2)的值已知x/y=2/7,求分式(x2-3xy+2y2)/(x2-2xy+y2)的值已知x/y=2/7,求分式x2-3xy+2y2/x2-2xy+y2的值已知y/x=1/2,求(x2+2xy+y2)/﹙x2-xy-2y2)的值. 已知x/y=3/5,求 (x2-xy+2y2)/(x2+2xy-y2)的值已知X>Y,x2+Y2=4xy.求(X+Y)/(X-Y)=? 已知x2+y2=12,x+y=4,求xy的值已知x-y=4,x2+y2=12,求xy的值已知x2-7xy+12y2=0,求x/y的值