已知实数x,y满足x^2+√2y=√3,y^2+√2x=√3,求x+y和xy的值

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已知实数x,y满足x^2+√2y=√3,y^2+√2x=√3,求x+y和xy的值
已知实数x,y满足x^2+√2y=√3,y^2+√2x=√3,求x+y和xy的值

已知实数x,y满足x^2+√2y=√3,y^2+√2x=√3,求x+y和xy的值
⑴若x=y,则x、y是方程m^2+√2m=√3的两个相等实根
由根与系数关系得:x+y=-√2,xy=-√3
⑵若x≠y,两式相减得:x^2-y^2+√2y-√2x=0,(x+y-√2)(x-y)=0
得:x+y=√2
两式再相加得:x^2+y^2+√2y+√2x=2√3
(x+y)^2-2xy+√2(x+y)=2√3
进而得:xy=2-√3

(1)当x=y时,由韦达定理得x+y=-√2,xy=-√3.(2),当x≠y时,两式相减得x+y=√2,xy=2-√3.

x^2+√2y=√3。。。。。。。。(1)
y^2+√2x=√3。。。。。。。。。(2)
所以x^2+√2y=y^2+√2x
x^2-y^2=√2(x-y)
(x+y)(x-y)=√2(x-y)
故x+y=√2
(1)+(2)得x^2+√2y+y^2+√2x=2√3
(x+y)^2-2xy+√2(x+y)=2√3
因为x+y=√2,所以2-2xy+2=2√3
xy=2-√3