Question

решитите по формуле дискриминанта пошла ​

Answer 1

$1. x^{2} +3x-54 = 0\\D = b^{2} - 4ac = 9 + 4*54 = 225, D > 0, 2 kornya\\x_1 = \frac{-b - \sqrt{D} }{2a} = \frac{-3 - 15}{2*1} = \frac{-18}{2} = -9\\ x_2 = \frac{-b + \sqrt{D} }{2a} = \frac{-3 + 15}{2*1} = \frac{12}{2} = 6\\\\2. 2x^{2} +3x-5=0\\D = b^{2} - 4ac = 9 + 40 = 49, D > 0, 2 kornya\\ x_1 = \frac{-b - \sqrt{D} }{2a} = \frac{-3-7}{2*2} = -\frac{10}{4}=-\frac{5}{2}\\ x_2 = \frac{-b + \sqrt{D} }{2a} = \frac{-3+7}{2*2} = \frac{4}{4} =1$

$3. 3. x^{2} -5x+6=0\\D = b^{2}-4ac = 25-4*6=1, D > 0, 2kornya\\x_1 = \frac{-b-\sqrt{D} }{2a} = \frac{5-1}{2}=\frac{4}{2}=2 \\x_2 = \frac{-b+\sqrt{D} }{2a} = \frac{5+1}{2}=\frac{6}{2}=3$