x^2-4y^2=-15,2y-x=3则x+2y=?

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x^2-4y^2=-15,2y-x=3则x+2y=?
x^2-4y^2=-15,2y-x=3则x+2y=?

x^2-4y^2=-15,2y-x=3则x+2y=?
x^2-4y^2=(x+2y)(x-2y)=(x+2y)*(-3)=-15所以x+2y=5

x^2-4y^2
=(x+2y)(x-2y)
=(x+2y)*(-3)
=-15
所以
x+2y=5 ...

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x^2-4y^2
=(x+2y)(x-2y)
=(x+2y)*(-3)
=-15
所以
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