1.
[tex]x^{2}+2x-3 = 0\\\\a = 1, \ b = 2, \ c = -3\\\\\Delta = b^{2}-4ac = 2^{2} -4\cdot1\cdot(-3) = 4 + 12 = 16\\\\\sqrt{\Delta} = \sqrt{16} = 4\\\\x_1 = \frac{-b-\sqrt{\Delta}}{2a} = \frac{-2-4}{2\cdot1} = \frac{-6}{2} = -3\\\\x_2 = \frac{-b+\sqrt{\Delta}}{2a} = \frac{-2+4}{2} = \frac{2}{2} = 1\\\\x \in \{-3,1\}[/tex]
2.
[tex]2x^{2}-5x+7 = 0\\\\a = 2, \ b = -5, \ c = 7\\\\\Delta = b^{2}-4ac = (-5)^{2}-4\cdot2\cdot7 = 25-56 = -31\\\\\Delta < 0, \ brak \ rozwiazania[/tex]
