РЕШИТЕ КВАДРАТНЫЕ УРАВНЕНИЯ ЧЕРЕЗ ДИСКРИМИНАНТ(в 2-в квадрате) 2Х в 2 +3Х-1=0 Х в 2+4Х-1=0 2Х в 2 +2Х-7=0

[latex]2 x^{2} +3x-1=0[/latex] [latex]D= b^{2} -4ac=3 ^{2} -4*2*(-1)=9+8=17[/latex] [latex] x_{1} = \frac{-b+ \sqrt{D} }{2a} = \frac{-3+ \sqrt{17} }{4} [/latex] [latex] x_{1} = \frac{-b- \sqrt{D} }{2a} = \frac{-3- \sqrt{17} }{4} [/latex] [latex] x^{2} +4x-1=0[/latex] [latex]D= b^{2} -4ac=4 ^{2} -4*1*(-1)=16+4=20[/latex] [latex] x_{1} = \frac{-b+ \sqrt{D} }{2a} = \frac{-4+ \sqrt{20} }{2}=-2+\sqrt{5} [/latex] [latex] x_{1} = \frac{-b- \sqrt{D} }{2a} = \frac{-4- \sqrt{20} }{2} =-2- \sqrt{5}[/latex] [latex]2 x^{2} +2x-7=0[/latex] [latex]D= b^{2} -4ac=2 ^{2} -4*2*(-7)=4+56=60[/latex] [latex] x_{1} = \frac{-b+ \sqrt{D} }{2a} = \frac{-2+ \sqrt{60} }{4}=\frac{-1+ \sqrt{15} }{2} [/latex] [latex] x_{1} = \frac{-b- \sqrt{D} }{2a} = \frac{-2- \sqrt{60} }{4}=\frac{-1- \sqrt{15} }{2} [/latex]