Решите уравнения: 1) 2x^2 - 3x + 5 =0 2) x^2 + 8x - вопрос №1223502281603322504224771376 от Akosh11 17.07.2020 05:56

Question

Алгебра: Решите уравнения: 1) 2x^2 - 3x + 5 =0 2) x^2 + 8x + 16 =0 3) 3x^2 - 2x - 5 =0 4) x^2 - 2x - 4 =0 5) x^2 -√3x - 1 =0

Akosh11 · Answer

1) 2x² - 3x + 5 = 0D = b² - 4ac = 9 - 4 × 2 × 5 = 9 - 40 = - 31 - корней нет.2) x² + 8x + 16 = 0D = b² - 4ac = 64 - 4 × 16 = 64 - 64 = 0 - имеет один кореньx = - b/2ax = - 8/2 = - 43) 3x² - 2x - 5 = 0D = b² - 4ac = 4 - 4 × 3 × (-5) = 4 + 60 = 64 = 8²x1 = ( 2 + 8) / 6 = 10/6 = 5/3 = 1 2/3x2 = ( 2 - 8) / 6 = - 14) x² - 2x - 4 = 0D = b² - 4ac = 4 - 4 × (-4) = 4 + 16 = 20x1 = ( 2 + 2√5) / 2 = 2( 1 + √5) / 2 = 1 + √5x2 = ( 2 - 2√5) / 2 = 2( 1 - √5) / 2 = 1 - √55) x² - √3x - 1 = 0- √3x - 1 = - x²√3x -...