Vin din viitor, unde le-ai mai postat.
[tex]\it 2x^2-x-3=0,\ \ a=2,\ \ b=-1,\ \ c=-3\\ \\ \Delta=b^2-4ac=(-1)^2-4\cdot2\cdot(-3)=1+24=25\\ \\ x_1,2=\dfrac{-b\pm\sqrt{\Delta}}{2a}=\dfrac{1\pm\sqrt{25}}{2\cdot2}=\dfrac{1\pm5}{4}\Rightarrow \begin{cases} \it x_1=\dfrac{1-5}{4}=\dfrac{-4}{4}=-1\\ \\ \it x_2=\dfrac{1+5}{4}=\dfrac{\ 6^{(2}}{4}=\dfrac{3}{2}=1,5\end{cases}[/tex]
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[tex]\it 2x^2+5x=0 \Rightarrow x(2x+5)=0 \Rightarrow \begin{cases} \it 2x+5=0 \Rightarrow 2x=-5|_{:2} \Rightarrow x_1=-2,5\\ \\ \it x_2=0\end{cases}[/tex]
