[tex]x_1+x_2=-\dfrac{-2}7=\dfrac{2}7\Rightarrow x_1=\dfrac{2}7-x_2\\\\x_1\cdot x_2=\dfrac{-14}7=-2\Rightarrow\left(\dfrac{2}7-x_2\right)\cdot x_2=-2\;\Big|\cdot 7,\\\\sau\;(2-7x_2)x_2=-14\Rightarrow 7x_2^2-2x_2-14=0[/tex]
Am ajuns deci la relaţia din enunţ, care se rezolvă cu clasica formulă:
[tex]x_{1,2}=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}.[/tex]
Green eyes.
