x2+y2=25 x+y=7 x>y 求x-y=?

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x2+y2=25x+y=7x>y求x-y=?x2+y2=25x+y=7x>y求x-y=?x2+y2=25x+y=7x>y求x-y=?x+y=7(x+y)^2=49x2+y2+2xy=492xy=24x

x2+y2=25 x+y=7 x>y 求x-y=?
x2+y2=25 x+y=7 x>y 求x-y=?

x2+y2=25 x+y=7 x>y 求x-y=?
x+y=7
(x+y)^2=49
x2+y2+2xy=49
2xy=24
x2+y2-2xy=1
x>y
x-y=1

x2+y2=25
x+y=7
(x+y)^2=49
x^2+y^2+2xy=49
xy=12
(x-y)^2=x^2+y^2-2xy=25-24=1
因为x>y
x-y>0
x-y=1

x=4,y=3.答案x=1

∵x2+y2=25 x+y=7
∴x2+Y2+2XY=49
∴2XY=24
∴X2-2XY+Y2=1
∴X-Y=1

非常谢谢您们！！！！

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