已知x-2y=3,2x^2-8y^2=5,则x+2y=

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已知x-2y=3,2x^2-8y^2=5,则x+2y=已知x-2y=3,2x^2-8y^2=5,则x+2y=已知x-2y=3,2x^2-8y^2=5,则x+2y=2x²-8y²=2

已知x-2y=3,2x^2-8y^2=5,则x+2y=
已知x-2y=3,2x^2-8y^2=5,则x+2y=

已知x-2y=3,2x^2-8y^2=5,则x+2y=
2x²-8y²
=2(x+2y)(x-2y)=5
所以x+2y=5/[2(x-2y)=5/6

2x^2-8y^2=2（x^2-4y^2）=2（x-2y）（x+2y）=5
又
x-2y=3
则
6（x+2y)=5
x+2y=5\6

2x^2-8y^2=5
2（x^2-4y^2）=5
（x+2y）（x-2y）=5/2
（x+2y）=（5/2）/（x-2y）=（5/20)/3=5/6

2（x∧2-4y∧2）=2（x-2y）（x+2y）=5，2×3×（x+2y）=5，
x+2y=5／6

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