已知x=根号5-2分之根号5-2,y=根号5+2分之根号5-2.求(1)x+y (2)xy (3)x+y分之x²
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已知x=根号5-2分之根号5-2,y=根号5+2分之根号5-2.求(1)x+y (2)xy (3)x+y分之x²+3xy+y²
已知x=根号5-2分之根号5+2,y=根号5+2分之根号5-2.求(1)x+y (2)xy (3)x+y分之x²+3xy+y²。(2和-2都在根号外)
已知x=根号5-2分之根号5+2,y=根号5+2分之根号5-2.求(1)x+y (2)xy (3)x+y分之x²+3xy+y²。(2和-2都在根号外)
x=(√5+2)/(√5-2)
=(√5+2)²/[(√5-2)(√5+2)]
=(9+4√5)/(5-2)
=(9+4√5)/3
y=(√5-2)/(√5+2)
=(√5-2)²/[(√5-2)(√5+2)]
=(9-4√5)/(5-2)
=(9-4√5)/3
(1)
x+y=(9+4√5)/3+(9-4√5)/3
=(9+9)/3
=6
(2)
xy=(√5+2)/(√5-2)*(√5-2)/(√5+2)=1
(3)
(x²+3xy+y²)/(x+y)
=[(x+y)²+xy]/(x+y)
=(6²+1)/6
=37/6
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再问: x, (√5-2)(√5+2)怎么是(5-2)
再答: x=(√5+2)/(√5-2) =(√5+2)²/[(√5-2)(√5+2)] =(9+4√5)/(5-4) =9+4√5 y=(√5-2)/(√5+2) =(√5-2)²/[(√5-2)(√5+2)] =(9-4√5)/(5-4) =9-4√5 (1) x+y=(9+4√5)+(9-4√5) =9+9 =18 (3) (x²+3xy+y²)/(x+y) =[(x+y)²+xy]/(x+y) =(18²+1)/18 =325/18
=(√5+2)²/[(√5-2)(√5+2)]
=(9+4√5)/(5-2)
=(9+4√5)/3
y=(√5-2)/(√5+2)
=(√5-2)²/[(√5-2)(√5+2)]
=(9-4√5)/(5-2)
=(9-4√5)/3
(1)
x+y=(9+4√5)/3+(9-4√5)/3
=(9+9)/3
=6
(2)
xy=(√5+2)/(√5-2)*(√5-2)/(√5+2)=1
(3)
(x²+3xy+y²)/(x+y)
=[(x+y)²+xy]/(x+y)
=(6²+1)/6
=37/6
希望能帮到你啊,不懂可以追问,如果你认可我的
回答请点击下方选为满意回答按钮,谢谢!
祝你学习进步!
再问: x, (√5-2)(√5+2)怎么是(5-2)
再答: x=(√5+2)/(√5-2) =(√5+2)²/[(√5-2)(√5+2)] =(9+4√5)/(5-4) =9+4√5 y=(√5-2)/(√5+2) =(√5-2)²/[(√5-2)(√5+2)] =(9-4√5)/(5-4) =9-4√5 (1) x+y=(9+4√5)+(9-4√5) =9+9 =18 (3) (x²+3xy+y²)/(x+y) =[(x+y)²+xy]/(x+y) =(18²+1)/18 =325/18
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