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Rezolvati urmatorul sistem:[tex] \left \{ {{x= \frac{20}{0,5y} } \atop { 5y^{2}-0,86xy-5=0 }} \right. [/tex]

Răspuns :

x=20/(y/2)
x=40/y
xy=40
5y²-0,86·40-5=0
5y²-34,4-5=0
5y²=39,4
y²=7,88
y₁=2,80
y₂=-2,80
x₁=40· 2,80=112
x₂=-40· 2,80=-112