已知xy=8满足x^2y-xy^2-x+y=56,求x^2+y^2的值

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/06 10:58:31
已知xy=8满足x^2y-xy^2-x+y=56,求x^2+y^2的值
xO; @!Y9J@ A  BF,B Mrw7ya'.|r7 O ;ƒ3%o&"LYhewۯ$ ߚlEIJOz,jw5UT4p&GAoUq.$y\lg󅘯@,#} E:,7*TFT&-HI[&R=qu"t2\8

已知xy=8满足x^2y-xy^2-x+y=56,求x^2+y^2的值
已知xy=8满足x^2y-xy^2-x+y=56,求x^2+y^2的值

已知xy=8满足x^2y-xy^2-x+y=56,求x^2+y^2的值
x^2y-xy^2-x+y=56
xy(x-y)-(x-y)=56
(xy-1)(x-y)=56
x-y=8
(x-y)^2=8^2
x^2-2xy+y^2=64
x^2+y^2=64+2xy
=64+16
=80

第一步提取x和y,得x(xy)-y(xy)-x+y=56提取xy得xy(x-y)-(x-y)=56得(x-y)(xy-1)=56所以7(x-y)=56,x-y=8,x^2-2xy+y^2=64